ber of new crayfish are described, and it would seem as if there were no limit to the number of species of this genus. The same journal contains a list of the grasshoppers of Illinois by Professor Cyrus Thomas, and a partial catalogue of the fishes of Illinois by E. W. Nelson. Insects. A notable paper, entitled "History of Phyciodes Tharos, a Polymorphic Butterfly," by W. H. Edwards, appears in the Canadian Entomologist. He finds that there are four generations of this butterfly at Coalburg, W. Va., the first of which is marcia and the second and third tharos, and none of the larvæ from these have so far been found to hibernate; and the fourth, under exceptional circumstances, has produced some tharos and more marcia the same season, a large proportion of the larvæ also hibernating. In the Catskill Mountains there are two generations annually, the first of which is marcia, or the winter form, and the other is the summer form. Mr. Edwards adds that, in a high latitude or at a high altitude, we might expect to find this butterfly with a single brood, and restricted probably to the winter form, marcia. And this is precisely what does occur in the island of Anticosti (about latitude 50°) and on the southern coast of Labrador opposite, tharos being the more northern form. All these varieties are produced, according to Mr. Edwards, by changes in climate or temperature. We would add that in this and similar cases studied by Weismann, we see species produced by causes easily understood and measured by the ordinary naturalist, and that phase of evolution called "natural selection" does not enter into the matter at all as a vera causa; and we doubt not that Darwinism, as such, has been much overestimated as a factor in producing species-a dogma being mistaken for a genuine cause. The annual report of Hayden's United States Geological and Geographical Survey of the Territories for 1875 contains a report of over two hundred pages, by A. S. Packard, Jr., on the Rocky Mountain locust and other insects either now or likely soon to be destructive in the extreme Western States and Territories. The report is fully illustrated, and contains maps showing the distribution of the locust, Hessian fly, wheat-midge, chinch-bug, army-worm of the North, the cotton army-worm, and the boll-worm. In the American Naturalist for July there is a critical notice of a work in Russian, by Ganin, on the metamorphosis of insects. The review has been prepared by Baron R. von Osten-Sacken. Some attention has been lately paid to stridulation, or the production of sound, in butterflies. Mr. A. H. Swinton finds that the costal vein of Ageronia feronia, a Brazilian butterfly, is bare, smooth, and elevated, which, when the wings are spread, is received into a concavity which is in every way suited to act as a clasp, and is sonorous when the wings are moved, while the whole apparatus represents the bristle and catch that lock the wings of the moths. Vanessa antiopa also stridulates. Mr. Swinton describes in the May number of the Entomologist's Monthly Magazine the various kinds. of apparatus in the moths, situated for the most part on the sides of the thorax, while some are said by Westwood to possess musical organs in the abdomen. Mr. M'Lachlan, in alluding to the Lepidoptera brought home by the Arctic Expedition, says that the larvæ of most of these species must of necessity require more than one season to acquire their full growth, for the short, fitful summer was utterly inadequate for the full development of most of the species; and, furthermore, it was probable that the pupa state might habitually last several years. Professor Westwood has noticed the habit, exceptional in the family Stylopida, of living as a parasite on a homopterous insect. An important paper by Professor Plateau on the phenomena of digestion in the harvestmen (Phalangium) brings out the fact that the so-called liver of these animals, as well as of spiders and Crustacea, is nothing else than the organ of secretion of a digestive fluid intended for the emulsionizing of grease and the dissolving of albuminoid substances. Professor Perez has studied the vitellogene cells of the ovaries of insects which give nourishment to the true egg cells of insects, as in certain Crustacea (Revue Scientifique, p. 1001). A new cave fauna, entirely distinct from that inhabiting Mammoth and other caverns in Kentucky, Indiana, and Vir ginia, has been discovered by Dr. Packard on the shores of the Great Salt Lake. The different species of animals (a helix, myriopod, harvestman, and poduran) inhabiting the cave are described in Hayden's Bulletin. Professor C. V. Riley's ninth report on the injurious insects of Missouri contains new and fresh information regarding the Western locust, the Colorado potato beetle, with maps illustrating their extension East. Other injurious insects are more or less fully treated. A work of a very high degree of interest to philosophic naturalists is Professor Weismann's "Studies on the Theory of Descent" ("Studien zur Descendenz-Theorie"), of which the second part has just appeared. It is divided into four sections, with the following subjects: "The Origin of the Markings of Caterpillars;" "On the Phyletic Parallelism in Metamorphic Species;" "On the Transformation of the Mexican Axolotl into an Amblystoma;" "On the Mechanical Conception of Nature." In the last chapter, which will interest thinkers, the author, while stating his belief that evolution has been accomplished mechanically, claims that this view of nature neither leads to materialism nor excludes teleology. In a recent essay on the origin of insects, Dr. Mayer, of Jena, suggests that the ancestor of the insects was winged. This view is opposed by Dr. Packard, who publishes a review of Mayer's essay in the American Naturalist for November, in which he maintains, with other writers on this subject, that they must have originated from larval forms, and claims priority for certain conclusions proposed as novel by Dr. Mayer. In a recent work on the morphology of the tracheal or respiratory system of insects, Dr. J. A. Palmen arrives at the conclusion that the primitive number of pairs of spiracles, or breathing-holes, in insects is eleven, thus agreeing with the views previously expressed by Packard in a brief essay published on the same subject in 1873. Palmen's work comprises one hundred and fifty pages, and is quite exhaustive. He believes that the tracheal system was at first, in its primitive form, open-i. e., consisting of a series of tubes connecting by spiracles or holes with the outer world. In certain aquatic insects the system became closed, the larva breathing by ex ternal gill-like appendages. As to the origin of the tracheæ, Bütschli (1870) believed that their mode of origin was the same as the silk-glands, and that the two sets of organs were homologues, and that they were derived primitively from the segmental organs of worms, which are arranged in pairs along the body of the latter animals. In 1873, Packard suggested that the air-tubes may have originated independently within the body, and afterwards formed a connection with minute pores leading through the skin. In 1874, Semper expressed the same views as those of Bütschli, which in the year after were accepted by Mayer. Moseley regarded them in 1874 as dermal glands modified. Packard then suggested that the tracheal system might be derived from the water vascular system of certain low worms; while, in a late paper on the development of the Lepidoptera, Hatschek conceives that the air-tubes are derived from respiratory portions of the skin much enlarged. Finally, Palmen appears to adopt the view that the trachea may have originated from the segmental organs of the jointed worms, which in turn originated from the dermal excretory glands of the lower unjointed worms. This shows how conjectural is our knowledge of the origin of these interesting organs. He conceives that the excretory function of the primitive lungsac was afterwards replaced by an absorbing function, and the sac or tube became a respiratory organ-viz., a trachea, which (at first simple and sac-like, due originally to an inpushing of the skin) became longer and branched, until it assumed the present form. With this view we should not be disposed to find fault as a provisional hypothesis. Sir John Lubbock, in a fourth communication to the Linnæan Society (reported in Nature) on the habits of bees and wasps, illustrated by ingenious experiments his modus operandi of testing their faculties, dispositions, habits, etc., by something of a double F apparatus, whereby an interval of three tenths of an inch, either by a drop from above or reaching upwards the distance from below, alone prevented ants from gaining access to a covered glass all filled with larvæ. They evidently had not the acumen to surmount the three tenths of open space, although they had for hours before been traversing the route and carrying off larvæ previous to the small gap being made. Industry was conspicuously shown by one specimen, which Sir John used to place in solitary confinement in a bottle for hours, and once for days; but the moment released it commenced its laborious larvæ-gathering propensities. It seems, from other experiments, that ants in difficulties within sight of their companions are by no means always assisted or relieved; other attractions, food and such like, possessing greater interest for them. On putting some specimens under the influence of chloroform, little or no notice was taken of those insensible by their companions, the tendency apparently being to let friends lie, and throw over the edge of the board strangers thus chloroformed. It seems that to get ants properly intoxicated with spirit for experimental purposes is no easy matter, some recovering too quickly and others remaining so thoroughly dead-drunk as to come under the rank of impracticables; while between reeling friends and strangers the experimenter finds himself baffled. The sober ants are exceedingly puzzled at finding their friends in such a condition. As a general rule, they picked up drunken friends and carried them to the nest, while they threw into the water and drowned strangers. In some instances confusion arose, for a few of the strangers were carried to the nest and friends tumbled into the water; but they did not return to the rescue of the friends, though strangers were afterwards expelled from the nest. Sir John expresses surprise that ants of one nest perfectly well know each other. Even after a year's separation old companions are recognized and amicably received; whereas strangers, particularly among the Lasius flavus, are almost invariably attacked and maltreated, even when introduced in the mixed company of old friends. Sight cannot be acute. For example: in experiments food was placed on a glass slip a few inches from the nest, the straight road to and from the nest being soon familiar to the ants; but when the food had been shifted only a short distance from its first position, it was long ere it was discovered. Indeed, they wandered from a few minutes to half an hour in the most extraordinary circuitous routes before finding out the direct road between the nest and food, and vice versa. Slavery in certain genera is a positive institution-the Amazon ants (Polyergus rufescens) absolutely requiring slave assistants to clean, to dress, and to feed them, else they will rather die than help themselves, |