The mite (Phytoptus oleivorus) is elongate, honey-yellow, o.14 mm. long, and with two pairs of four-jointed legs, each terminating in a curved spine, with opposing bristles. The eggs are laid singly or in small clusters on the leaves. They are spherical, transparent, with a yellow tinge, and hatch in summer in four days. The cast mite skins adhere, as stated above, to the surface of leaf or fruit. The food of the mite is the essential oil which abounds in the succulent parts of citrus plants. It is stationary when feeding, but moves actively, and wanders front one part of the plant to another, especially to new growths. Thousands occur on a single leaf, 75,000 having been computed by Mr. Hubbard in winter time on a leaf averaging fifteen square inches. They are still more numerous in summer.

Rust rings encircle the fruit much as the ecliptic does the earth. There is a penumbral band between brightest sun and deepest shade, indicating the preference of the mite for such half shade. Frosts kill the mites, but not the eggs. Drouth causes both to dry up. Birds, insects, and especially spiders, are the chief agencies in distributing the mites from place to place. The effect of the mite on the fruit, aside from the rusty appearance, which lowers the market value, is in nowise injurious, as the quality is, if anything, improved, and the disposition to rot decreased. The effect on the leaf is to slightly check growth.

The mite is generally distributed in Florida, but not elsewhere. Like most mites affecting growing plants, it is worse on high, dry lands than in low, moist ones.

No method of culture or of manuring-in fact, no method that does not comprehend the true cause, has proved of avail to prevent the rust. Wind-breaks and isolation act as preventives, but insecticides are the only remedial agencies; they must, however, kili mites, eggs, and molting mites. Whale oil soap, one pound to five gallons of water, in early spring before new growth begins, and weaker solutions at frequent intervals, cause the mites to fall to the ground. Flowers of sulphur is deadly to the active mites, but not to the eggs. Kerosene emulsions, as used against scale-insects, with sulphur added, are the most satisfactory.

Dr. E. P. Howland read a paper on THE EFFECT OF ANÆS THETICS ON ANIMALS, explaining the new invention of Paul Bert,

SIXTY-SECOND MEETING, April 19, 1884.

The President occupied the chair. Forty members were present. Dr. Cyrus Thomas read a paper on THE GROWTH OF TREES AS A MEANS OF DETERMINING THE AGE OF MOUNDS. The long accepted theory that the age of a tree is indicated by the number of concentric rings can no longer be considered tenable. The only way of testing this theory is by cutting down trees the age of which is known. This has been done in many instances, which were cited, and the result has been the demonstration of the falsity of the long accepted theory.

Mr. John Murdoch made remarks on DREDGING AND MARINE COLLECTING AT Point Barrow, detailing his experiences as naturalist of the Signal Service Station at that place.

Dr. Bean, in a paper on THE DISTRIBUTION OF THE SALMONIDÆ IN ALASKA, enumerated the following twenty-one salmonoids as occurring there:

Osmerus dentex, Osmerus spirinchus, Mallotus villosus, Hypomesus olidus, Hypomesus pretiosus, Thaleichthys pacificus, Thymallus signifer, Stenodus Mackenzi, Coregonus Laurette, Coregonus near Merkii, Coregonus quadrilateralis, Coregonus Kennicotti, Coregonus Nelsonii, Salvelinus malma, Salmo purpuratus, Salmo Gairdnerii, Oncorhynchus chouicha, Oncorhynchus keta, Oncorhynchus nerka, Oncorhynchus kisutch, Oncorhynchus gorbuscha.

Osmerus is known to range only from the Bristol Bay region to the extreme northern limit of the Territory. O. dentex is quite similar in appearance to O. eperlanus and O. mordax of the Atlantic. O. spirinchus may be simply the spent condition of dentex. In the region in which they occur the smelts are quite abundant, and are extensively used by the natives for food, both fresh and dried.

Mallotus villosus is found in every portion of the Territory, being extensively eaten by the natives, and forming one of the best known foods for the codfish in the Gulf of Alaska.

Hypomesus is represented by two species, one of which, H. olidus, is confined to the western shore of Alaska, being most abundant to the northward. H. pretiosus is known only from the Gulf of Alaska. H. olidus spawns in fresh-water ponds, while H. pretiosus is a surf spawner.

Thaleichthys pacificus (the Eulachon) occurs in the Gulf of Alaska at least as far west as Katmai, in Shellikoff Straits, where it is preserved in salt and considered quite a delicacy. The Eulachon. literally swarms in the southeastern part of the Territory, and is utilized both in a fresh state and for the manufacture of a fat or oil which the natives use in place of butter, and which has been experimented with as a substitute for cod liver oil.

Thymallus is known to occur from the Bristol Bay region to the extreme northern limit of the Territory, abounding in the rapid rivers. It takes the artificial fly quite readily, according to the testimony of Lieut. Schwatka, and is generally considered an excellent food-fish. To the eastward it is known to reach the Mackenzie river region.

Stenodus might be called the giant white fish. It reaches 50 pounds in weight, and has been recorded as growing to a length of 5 feet. We have it only from the Yukon river region. It was described, however, from the Mackenzie, and occurs also in the tributaries of that river. It is one of the finest food-fishes of Alaska.

The most widely distributed of the species of Coregonus is C. quadrilateralis, which we now have from the Yukon river region southward to Kodiak. C. Laurette is also pretty widely distributed, at least from the Kuskoquim to Point Barrow. The species related to C. Merkii is a small northern form, which is not of much importance as a food-fish. C. Nelsonii is a hump-back species, not important as a food-fish, ranging from the northern limit of the Territory southward to the Yukon, at least, and probably to the Kuskoquim. C. Kennicottii ranks next in excellence to Stenodus. It is said to reach 30 pounds in weight, and its range is from the Kuskoquim to the northern limit of Alaska. All the Coregoni are important for food except C. Nelsonii and C. Merkii, sub-species.

Salvelinus is abundant throughout the Aleutians and the mainland of Alaska, north to Colville river. In the northern portion of its range it grows to an enormous size, reaching fully 12 pounds in weight. In the sea-run condition it is extensively salted at Kodiak, and exported as salmon trout.

Salmo purpuratus is found in southern Alaska and on the island of Kodiak and Unalashka. It is extremely abundant and attains a weight of 20 pounds. S. Gairdnerii occurs in southern Alaska and

westward to the Bristol Bay region. It is also known from the islands of Unalashka and Kodiak. It grows to a weight of 30 pounds, and is a very important food-fish.

One species of Onchorhyncus, O. gorbuscha, extends over the whole coast of Alaska northward to Colville river. All the rest extend at least as far as the Yukon river, and one species, O. keta, has been obtained from Hotham Inlet. The Onchorhynchi are the most important food-fishes of the Territory, and are the most abundant. The principal centers of export are Kodiak and Cook's Inlet. Numerous canneries have sprung up lately in these regions, directing their attention mainly to the red-fish, O. nerka, a salmon whose flesh is beautifully red, but comparatively inferior. The finest of the salmon, O. chouicha, is employed principally for salting, the bellies only being selected for this purpose; the remainder of the fish is made into ukali.

SIXTY-THIRD MEETING, May 3, 1884.

The President occupied the chair.

ent.

Twenty members were pres

He

Prof. Theodore Gill read a paper ON THE SYSTEM OF THE SQUALI. These belong to the Selachians, which constitute a class quite distinct from the fishes and widely separated from the Ganoids. briefly reviewed the salient structural features of the various representatives of the order Squali, as well as the history of the classification of the group, and concluded with the assertion that there appeared to be five principal types of structure manifested in the various forms whose anatomy is more or less satisfactorily known.

(1.) The Pternodonta or Selachophichthyoidei are represented by but one known species, lately described by Mr. Garman. Its anatomical characteristics are unknown, but will probably be found to be nearly the same as in the succeeding group, Opistharthri. It is distinguished from all other known sharks by the very elongated and almost anguilliform shape as well as by the peculiar teeth, which have long fixed bases and are not reclinable as in most of the other types. It was also predicted that the Pternodonta would probably be found to have the palato-quadrate element articulated

with the posterior portion of the skull behind the orbits, and the vertebral column non-segmented or notochordal.

(2.) The Opistharthri are sharks with the palato-quadrate apparatus articulated with the post-orbital processes of the skull, and a persistent notochord, inferior mouth, and the branchial apertures in increased numbers. The Notidanidæ or Hexanchidæ are the only forms.

(3.) The Proarthri are sharks with the palato-quadrate apparatus articulated with the anterior orbital region of the skull, the vertebral column segmented, the mouth sub-terminal, and the forehead declivous. The Heterodontidæ, represented by the well-known "Port Jackson Shark," form the only existing family.

(4.). The Anarthri are sharks with the palato-quadrate apparatus not articulated directly with the skull, the vertebral column variable but more or less segmented, and the mouth inferior. To this group belong all living sharks, excepting those now specifically eliminated.

(5.) The Rhina are sharks with the palato-quadrate apparatus also not directly articulated with the skull, the vertebral column segmented, the mouth terminal (both jaws being advanced well forwards), and the pectorals developing enlarged anterior basal lobes which are separated by notch-like spaces from the branchial regions. To this belongs the family Squatinidæ, including the socalled angel-sharks.

The speaker was inclined to consider several of these more than sub-ordinal, and rather as of ordinal, value, but until they had been better studied he would reserve opinion on this question. He would now only add that the first and second groups might be combined in one order, the third isolated in another, and the fourth and fifth segregated in a third.

There was also one type represented by the extinct Cladodontidæ, whose position is doubtful. For these he had formed the group Lipospondyli, but it is not evident whether it belongs with the true Squali or whether it may not be related to the Holocephali, the character of the branchial arches being dubious.

Mr. N. P. Scudder read a paper on CERTAIN ANATOMICAL DETAILS IN THE MUSKRAT, and exhibited specimens of the skeletons of muskrats, showing the number of the lumbar vertebræ to be six and not three as stated by Professor Flower. He also showed that