sheet might thus be formed. Great cold prevailing on its northern limits and serving as a barrier to its motion in that direction, there being at the same time a partial melting of its southern face, the waters from the wasting snows on its surface percolating the icy mass, there also being contractions and expansions consequent upon alternations in the temperature; all these being connected with the gravitating force of a mass from five thousand to ten thousand feet in thickness, motion to the south would inevitably result, even on a horizontal surface, and much more if there were a southward inclination of the country. Under these circumstances we have an instrumentality fully able to plane, smooth, and striate the rocky floor of the continent as it now appears, and thus to account for the debris almost everywhere met with in great abundance. But if there were no elevation of the country, how are we to explain the occurrence of pot-holes in places apparently never traversed by torrents; the formation of flords; the existence of sub-marine riverchannels, as those extending from the mouths of the Hudson and the Connecticut; or the fact of sub-aërial deposits, as mud-flats, now found beneath the level of the ocean? It is well known that, when glaciers meet with obstructions, breaks (known as moulins) occur in them; that the snows melting on the surface of the ice-mass, streams are formed, which flow into these breaks, and thus become torrents and cascades, which wear pot-holes in every respect similar to those requiring explanation. Again it should be remembered that such an ice-sheet moving seaward must, in displacing the waters along the shallow margin of the ocean, do its legitimate work of erosion, and that thus old depressions would be deepened, while new valleys and fiords would be formed, as well as sub-marine river-channels, which remain to this day. Accordingly all this erosion might readily take place without an elevation, even if the sea were at its present height. But this leads us to ask, whence came the immense ice-sheet; undoubtedly for the most part from the ocean. Thus its waters must have undergone a great depression, perhaps one of several hundred feet; and this enables us to account for the mud-flats and other like deposits, which were probably laid down when the ocean was at a lower level than it is to-day. It has been, moreover, thought necessary to suppose that a depression of the continent finally followed its conjectured elevation. The land having been lifted up, it must be got down again, in order that there might be a return of warmth, and things be as we now find them. Now marine organic remains seem to attest a depression, in some places, of about five hundred feet. But so slight a submergence of the land, there being upon it an ice-sheet thousands of feet in thickness, could not cause a return of warmth, while the cosmical agencies already referred to are abundantly sufficient for the production of such an effect. This summer of the ages thus coming on, the ice-sheet as gradually melting must retreat northward. And the waning of the glacial mass would be accompanied by results which require an explanation. The ice thawing, the detrital matter which lay beneath it, and is now known as typical drift, would be laid bare and left substantially as we find it. In this view a resort to a depression of five thousand or six thousand feet, and to iceberg agency, is unnecessary. Indeed, Arctic icebergs could not furnish the material of New England typical drift, since it is for the most part of local origin; while bergs of ice from the White Mountains could not have supplied it, for it is a continuous sheet, having a uniform glaciated character, spreading over vast areas lying far to the north of these mountains. So icebergs could not have deposited it, because, as they slowly wasted, the particles of matter must have been scattered by the flux and reflux of the tides, and thus to a large extent stratified. Again, from the southern border of the wasting icesheet, floods of water would flow, working over and remodeling portions of the detrital masses, bearing some of the finer material southward, and laying down those deposits known as modified drift. These constitute in part the terrace formations, which usually slope with the rivers along which they occur. In some instances there were barriers obstructing the waters; thus were formed ponds and lakes, in which deposition took place in more nearly horizontal layers. Finally from the wasting of the ice-sheet the surface of the ocean must be elevated, its waters spread over the lower levels of the still slightly depressed lands, laying down beds containing marine organic remains, which to-day bear witness of a partial depression. In due time, after the disappearance of the ice-sheet, the continent would resume its normal elevation, the brackish waters of the ocean be excluded, and all things come gradually to take the position in which we now find them. In conclusion it may be asked whether the explanation suggested be not in consistency with the facts, and thus whether we ought not to accept it, rather than arbitrarily to resort to the assumption of a vast continental elevation and depression, which if not disproved, is at least unsupported by positive evidence. Mr. DALL described three new generic forms of Brachiopoda, principally from the collections of the United States Exploring Expedition. Two of these belonged to the group of articulated Brachiopods, while the third was that animal, which, under the name of Lingula, had just been described by Mr. Morse. Mr. Dall then spoke of several special points of structure, especially the peduncle of Lingula, demonstrating its construction to be analogous to that of the siphons of bivalve mollusks, such as the common clam, Mya arenaria. He then described the bristles of Lingula, showing that they were quite different in construction from those of the worms, and also that the Chitons were (in some genera) provided with true follicular setæ, proceeding from the mantle. Hence these characters cannot be held to afford satisfactory evidences of affinities with Annelids. Mr. Dall then proceeded to discuss the theory of Mr. Morse, that the Brachiopods were a subdivision of the Annelids. Mr. Dall took the opposite view, and, while admitting all the facts brought forward by Mr. Morse, and fully appreciating the careful and thorough nature of his researches, contended on the other hand that these facts were susceptible of quite another interpretation. Mr. Dall then went on to take up, one by one, the circulatory, nervous, muscular, and digestive systems of the Brachiopods, and to compare each with the same organs in the Annelids and the Mollusks, and came to the conclusion that the weight of structural characters was essentially of a Molluscan nature. The Mollusks were an individualized type, while the Annelids, and even most of the Articulates were typified by their repetition of similar organs. No such repetition obtains among the Brachiopods. Mr. Dall was of the opinion that the Molluscoidea should rank as one of two great primary divisions of the Mollusca-one, the true Mollusks, typified by the Gasteropoda, and second the Molluscoidea, typified by the Brachiopoda. The second division would include the Polyzoa, Tunicata, and Brachiopoda, and Mr. Dall was of the opinion that these groups were essentially related to one another, and cannot be separated without violence to their affinities. In reply to Mr. Dall's communication and objections advanced, Prof. Morse replied in brief as the time for adjournment had passed. He would only take a few moments in correcting some points in which Mr. Dall had evidently misunderstood the general articulate characters claimed for the Brachiopods. In this respect his demonstration of the striated muscular fibre in the Brachiopods accorded well with the views advanced, inasmuch as striated muscular fibre is a great characteristic of the crustacea, and does not occur in the mollusks. Mr. Dall did not know of any tubicolous worms having a blind intestine. Professor Morse referred him to certain worms in the inferior groups. His views on Chiton were rather strange, seeing that Chiton presented articulated characters in its development, the presence of a dorsal vessel, the terminal opening of intestine, and the forward opening of oviducts. As to a comparison between the peduncle of Lingula and the syphonal tubes of Mya, the relations were so different that they could not enter the discussion whatThe related points, as indicated by the structure of the oviducts, were not properly appreciated by Mr. Dall. He referred to the figure still kept upon the board as presenting all the points involved, and would demand a molluscan character in the Brachiopods. He then carried out the points raised by Mr. Dall, by citing other mollusks, with strong articulated features, which Mr. Dall had overlooked. ever. Mr. THOMAS MEEHAN read a paper "On the Laws of Fasciation, and its relation to Sex in Plants." He said that in trees, branches often came out in thick masses, which botanists called "fasciations," and the people "Crow's Nests." An over supply of nutrition was the received theory of their origin. He believed the reverse to be the fact. In proof of this he stated that the shoots forming the bunch of branches never grew as vigorously as the others, the leaves were of a paler hue, and in evergreens, the leaves were deciduous. Many of the shoots died in severe winters. All these results were due to imperfect nutrition, the effect of which was a low state of vitality. That weakness produced the fascicle was also proved on the theory propounded in his Chicago paper, “Adnation in Coniferæ." There it was seen that distichous leaves in coniferæ came only with increased vigor of growth. The leaves were less free from cohesion with the stem in proportion as vitality was low. Here were the same facts. The leaves on the fascicle of the Balsam Fir were of the same nature as the weak leaves described in the paper referred to. Mr. Mechan had also shown, at the Salem mecting, that sex was influenced by the condition of vitality. The male sex followed from a loss of vigor. Here the same law followed fasciation. The fasciated bunches in the Blackberry, produced foliaceous calyx sepals; and where the bunches were of numerous branchlets, an increase of petals followed. In a variety known as Willson's Early, the number of branchlets in the bunch was often greater than in other instances. Then the female organs were nearly all aborted, and the flowers were completely double. Thus proving at once that weakness was unfavorable to the female sex, and proportionately favorable to fasciation. The conclusion reached, was that fasciated branches, or "Crow's Nests," are the consequence of impaired nutrition or vitality. Mr. THOMAS MEEHAN read a paper "On objections to Darwin's Theory of Fertilization through Insect Agency." He said that the discoveries of Darwin had disclosed wonderful apparent arrangements for fertilization through insect agency; but occasionally instances were found where with the most perfect facilities insects seemed to make no use of them. These had been considered as objections to a full acceptance of Mr. Darwin's theories. The Salvia was an instance. The lower division of the anther acted as a petaloid lever, closing the throat of the corolla tube, which ought to throw the pollen on the back of the bee when it entered for the honey. The principle was perfect. But no insect is seen to enter. On the other hand the Humble Bee, “without which,” Darwin says, “some species would die out in England," bores a hole on the outside, through which it gets the honey. The Humble Bee thus seems to avoid its duty here. A similar state of things exists in the Petunia of our gardens. The humble bee extracts the honey by making a slit in the tube, and avoids interference with the pollen. But Mr. Meehan found that these flowers are the favorite resort of Sphinx's and other night moths, which do extract the honey from the mouth of the tube, and thus cross fertilize. It would thus seem that plants not only do as a rule prefer fertilization by insect agency, but probably some classes of flowers have their preferences for certain classes of insects. In the case of Salvia, probably some insects peculiar to their native countries, fertilize them; especially is this probable, as in cultivation the Salvia produces very little seed. THE AMERICAN NATURALIST. Vol. IV. NOVEMBER, 1870.-No. 9. THE HABITS AND MIGRATIONS OF SOME OF THE MARINE FISHES OF MASSACHUSETTS. THE part of Natural History relating to the habits of fishes is far behind other branches of this study, comparatively little being known of this interesting subject. The reason of this is plainly understood when we consider how small is the number of persons interested in such studies, who have the opportunity of observing the fishes a sufficient length of time to enable them to gain any great amount of information concerning them. Those who have the opportunity for gathering such information are of the class who look more to the financial profit from this business than to the benefit in knowledge they may gain. There is fortunately another class of individuals, who, while striving for their own maintenance, are careful to record the numerous Entered according to Act of Congress, in the year 1870, by the PEABODY ACADEMY OF SCIENCE, in the Clerk's Office of the District 65 (513) |