In the study of the hyoid bone of certain parrots, Mr. Mivart finds that the whole order of Psittaci is distinguished from every other order of birds by the shape of its hyoid. The distinctive characters are (1) Basihyal much broadened posteriorly. (2) Basihyal developing on either side a forwardly and upwardly directed process. (3) An os entoglossum in the form of a single broad bone with a considerable central foramen, or, in the form of two lateral parts, entoglossals, medianly united in front by cartilage and leaving a vacant space between this and their attachment behind to the basihyal. (Proceeds. Zool. Soc. London, 1895, p. 162.)

MAMMALS. Mr. Outram Bangs distinguishes the Skunks of eastern North America as follows:

Mephitis mephitica (Shaw), ranging through the Hudsonian and Canadian zones of the east, south to about Massachusetts.

Mephitis mephitica elongata (Bangs), found in Florida and the southern Atlantic states and ranges north to about Connecticut.

Both of these species differ from the western skunks, which form a separate group.

Among the latter the author recognizes Richardson's Mephitis americana var. hudsonica as a good species which must therefore bear the name M. hudsonica (Richardson). It is the largest of all the skunks, and has an extensive range in the northern prairies, extending east as far as Minnesota. (Proceeds. Boston Soc. Nat. Hist., Vol. XXVI.)

ENTOMOLOGY.'

Insects in the National Museum.-The staff of the Department of Insects of the U. S. National Museum has been reorganized, as a result of the sad death of the former Honorary Curator, Professor C. V. Riley.

The reorganization has been effected by the appointment of Mr. L. O. Howard, Entomologist of the U. S. Department of Agriculture, to the position of Honorary Curator to the Department of Insects; of Mr. Wm. H. Ashmead to the position of Custodian of Hymenoptera, and Mr. D. W. Coquillett to the position of Custodian of Diptera. All museum custodians are honorary officers. Mr. M. L. Linell will remain as general assistant to the Honorary Curator.

The Department is, at present, in excellent working condition. It contains a very great amount of material in all orders, and, in many

1 Edited by Clarence M. Weed, New Hampshire College, Durham, N. H.

unusual directions, surpasses any collection in the country. Among others, the following are of especial interest :

(1) The large collection, in all orders, of the late Dr. C. V. Riley. (2) All of the material gathered during the past 18 years by correspondents, field agents, and the office staff of the Division of Entomology, U. S. Department of Agriculture.

(3) The greater part of the collection of the late Asa Fitch.

(4) The large collection, in all orders, of the late G. W. Belfrage. (5) The collections in Lepidoptera and Coleoptera made by Dr. John B. Smith down to 1889, together with the types of the Noctuidæ. since described by Dr. Smith.

(6) The collection of the Lepidoptera of the late O. Neske. (7) The collection of Lepidoptera of G. Beyer.

(8) The collection of Coleoptera of M. L. Linell.

(9) The bulk of the collection, in all orders, of the late H. K. Morrison.

(10) The collection of Diptera of the late Edward Burgess. (11) The type collection of Syrphidæ made by Dr. S. W. Williston. (12) The collection of Ixodide of the late Dr. George Marx. (13) The collection of Myriopoda of the late C. H. Bollman. (14) Sets of the neo-tropical collections of Herbert Smith. (15) The collection of Hymenoptera of Wm. J. Fox. (16) The collection of Tineina of Wm. Beutenmuller.

(17) The large Japanese collection, in all orders, of Dr. K. Mitsukuri.

(18) The African collections, in all orders, of Dr. W. S. Abbott, Wm. Astor Chanler, J. F. Brady, the last "Eclipse" expedition to West Africa, and of several missionaries.

(19) The large collection from South California of D. W. Coquillett, in Coleoptera, Hymenoptera, Lepidoptera and Orthoptera.

(20) The Townend Glover manuscripts and plates.

In addition to this material, there are minor collections which have been the result of the work of government expeditions, or are gifts from United States Consuls and many private individuals.

This enormous mass of material is being cared for by the active and honorary forces of the Department, and the perpetuity of the collection is assured. The National Museum building is fireproof, and this, together with the fact that it is a national institution, renders the Department of Insects perhaps the best place in this country for the permanent deposits of types by working specialists in entomology, and for the ultimate resting-place of large collections made by individuals.

The policy of the Museum at large, with regard to the use of its collections by students, is a broad and liberal one. Students are welcome in all departments, and every facility is given to systematists of recognized standing.

On the Girdling of Elm Twigs by the Larvæ of Orgyia leucostigma, and its Results.-The white-marked tussock-moth Orgyia leucostigma, has, for a long term of years, been exceedingly destructive to the foliage of the elms, horse-chestnut and fruit trees in Albany. Fruit trees of considerable size have been killed by their defoliation within a few days, toward the maturity of the caterpillar. Large elms and horse-chestnuts have had the foliage entirely consumed, only the ribs and principal veins remaining.

In the summer of 1883, a new form of attack by this insect was observed by me in Albany. About the middle of June of that year, the sidewalks, streets and public parks where the white elm, Ulmus americana was growing, were seen to be thickly strewn with the tips of elms two to three inches in length, bearing from four to ten fresh leaves, and comprising nearly all of the new growth of the season. On examination, it was found that above the point where the tips had been broken off, the bark had been removed for an extent averaging about r of an inch, apparently by an insect.

As the Orgyia larvæ were then occurring in abundance on the trees, they were suspected as being the authors of this injury, and the suspicion was verified by ascending to a house-top, where the roof was found to be heaped in the corners with the severed tips, and the caterpillars engaged upon the branches in the girdling. The explanation of the breaking-off was simple. With the removal of the bark, the decorticated portion-not exceeding, in many instances, in thickness the diameter of a large pin-dried, and becoming brittle, was readily broken by a moderate swaying of the wind.

The girdling of the twigs in this manner could serve the Orgyia no such purpose as attends the girdling of several other insects, as the Elaphidion pruners of oaks and maples, where it enables the insect to attain greater security for its transformations through this method of reaching the ground, or the Oncideres twig-girdler, where the dead wood affords suitable food for the larva. Probably the conditions of growth during the spring of this year were such as to render the young bark at the point attacked particularly attractive to the larvæ; but why, after feeding upon it to so limited an extent, it should cease and resume its feeding on the leaves, can not be explained. In a few in

* Read before the American Association for the Advancement of Science, at its Springfield meeting, Sept. 3, 1895.

stances where the twigs had become detached quite near the node marking the commencement of the year's growth, the bark had been irregularly eaten for an inch or more in extent.

While the Orgyia is a serious pest in Albany, it has its years of remarkable abundance and of comparative scarcity. Girdled tips, as above described, have been seen each year since 1883, but by no means corresponding in number to the degree of abundance of the caterpillar. My attention had not been drawn to them the present year, until much later than the usual time-toward the end of August. At this time (21st of August), many tips of unusual length and with perfectly fresh leaves were collected from beneath a large American elm. Each one had broken at the base of the girdling, which had probably been quite near the node of the year's growth. They were of special interest from their great length, varying from 10 to 18 inches. From the growth they had attained, it was evident that the girdling had not been done in the spring or early summer, but in the late summer after the usual brood had completed its transformations. It was clearly the work of a second brood of the insect, and this was confirmed by my having seen, a few days previously from a house-top, while making observations on the elm leaf beetle, the Orgyia larva about one-half grown.

A distinct second brood of the Orgyia has not been recorded in Albany, although it is known to be double-brooded in Washington and Philadelphia, and probably in Brooklyn, and has also been observed in Boston. The present year, however, has been an exceptional one in the remarkable abundance, the rapid development, and the injuriousness of several of our more common insect pests.

Another interesting feature connected with these tips was the illustration they gave of the manner in which woody structure is built up -the sap ascending through the sap-wood, and, after its assimilation in the leaves, returning through the inner bark and depositing its organized material. The bark above the girdling, in healing in a rough and irregular manner, had swollen out at this point in a bulbous-like enlargement, showing very clearly the arrest and deposit of the returning sap consequent on the absence of its natural channels, and the drying and the death of the decorticated wood below it. In a specimen. gathered in which the node of the preceeding year remained attached to the fallen twig, the diameter of the new growth above the bulb was at least twice that of the starved node below.

This peculiar form of Orgyia attack has not been seen upon the horse chestnut, maple, apple or plum, or any of its other food-plants. J. A. LINTNER.

Albany, N. Y.

EMBRYOLOGY.'

Experimental Embryology.--Recent numbers of Roux's Archiv für Entwickelungsmechanik contain numerous additions to our knowledge of the possibilities resident in the early stages of the development of animals, possibilities unsuspected till direct experimental interference made them evident.

T. H. MORGAN of Bryn Maur presents evidence to show that two blastulæ of the sea urchin, Sphærechinus, may fuse together and form one embryo. When eggs are shaken just after fertilization they may loose their membranes and afterwards some of the resulting blastulæ are found to have twice the normal size though otherwise like the usual blastulæ in appearance. Such large blastulæ are stated to arise from the fusion of two common blastulæ.

Notwithstanding this complete fusion the future development of such enlarged blastulæ gives evidence of their dual origin. At the gastrula stage two invaginations are formed.

One may be much the greater and the two may not appear at the same time. The two invaginations stand in no fixed relation to one another and may appear in all parts of the compounded blastula.

Later the larva that develops from two fused blastulæ tends to develop two sets of arms and two systems of skeletal rods, but those accompanying the lesser invagination are much reduced in size and less perfect than the rods associated with the main invagination.

A second paper by the same worker records a variation in the cleavage of the above sea urchin when some of the eggs were shaken. While most of the eggs divide into 2, 4, 8 and 16 cells some were found to divide at once into three. These 3 cells are elongated parallel to the planes that produced them. When they next divide they all do so lengthwise, in flat contradiction to "Hertwig's law." These six equal cells lie in a plane at right angles to the two cleavage planes that have produced them.

Such eggs may develop into gastrula. They form six small cells or micromeres at one pole of the mass in place of the normal four. The author thinks a micromere field must have been present in the egg prior to division."

1 Edited by E. A. Andrews, Baltimore, Md., to whom abstracts, reviews and preliminary notes may be sent.