ed as invaginations of the "ectoderm," but both sorts of canals arise as independent lacunae, subsequently acquiring an epithelium and connecting together, and the chambers are formed from groups of the immigrated cells. The development of Spongilla is thus brought into accord with that of the marine cornacuspongiae.

In a comparative review of the various types of sponge development, the author points out the fundamental similarity between the development of the cornacuspongiae and that of the calcareous sponges, as exemplified in Sycandra. The ciliated cells are homologous in the two kinds of larva, as are the granular cells of the amphiblastula and the inner mass of the other larva. The difference in the character of the metamorphosis arises from the fact that in the amphiblastula there is a large cavity, while in the larva of cornacuspongiae there is none. In this comparison Wass and Delage agree.

The author thinks the development of those sponges (Ascetta, Oscorella, Plurira, etc.), which apparently differ from the plan of development described in this paper, needs to be worked over. A fundamental harmony with the development of cornacuspongidae and Sycandra will be revealed.

Touching the relationship between sponges and the other metazoa the author, without dogmatizing, is inclined to believe that they had a common ancestor above the protozoa. This ancestor is represented in the two-layered larva of both. But the community of origin goes no higher than this simple form-the sponges are not coelenterates. In the two-layered ancestor of the sponges, the superficial ciliated cells migrated into the interior, resigning their function of locomotive organs in order to generate internal currents of water, made necessary by the adoption of a fixed habit of life with subsequent increase of bulk. In other metazoa, the ciliated cells continue to form the superficial covering of the body. The immigration of the ciliated cells in the larva of cornacuspongiae, and the invagination of the ciliated cells in the Sycandra amphiblastula, are the ontogenetic expression of this change of position of the ciliated cells in the early ancestors of sponges, and have nothing to do with a process of gastrulation-the twolayered embryo being already formed before the occurrence of this immigration or invagination.

H. V. WILSON.

ENTOMOLOGY.'

Shade Tree Insects.-Professor H. Garman' publishes an excellent account of the pests of shade and ornamental trees. The article is chiefly concerned with insect pests, which are roughly divided into three groups: (1) Leaf insects, (2) trunk and branch mining insects, and (3) root infesting insects. To the first group belong the largest proportion of species, the walnut-worm, web-worm, elm leaf-bettle and others being included in it. "Such insects attract attention at once from the nature of their injury, the unsightly appearance due to gnawed leaves, webbing and refuse, taking away at once from trees their practical value as shade, and their æsthetic value as ornament.

"While their injuries are not at first so apparent, the work of the boring and 'mining species is not less injurious, and is the more to be feared because its results are not seen until the mischief under the bark is at an advanced stage. The locust borer and the elm bark-beetle are members of this group, both species being common and injurious in Kentucky. The pine bark-beetles and the fruit bark-beetles now becoming injurious in this State may also be placed here. The greater

number of species which attack the trunk are the grubs of beetles. A few are caterpillars (larvæ) of moths. The branches and twigs are injured by a host of small species, some of which girdle them, others mine them, still other species do serious mischief by placing their eggs in them, while some of the true bugs simply puncture and abstract their

sap.

"Doubtless the number of insects which feed on the roots of shade trees is large, but the unavoidable difficulties in the way of studying their habits has prevented a very full knowledge of this group."

Mr. Garman treats of the life-histories of the species most destructive in Kentucky at some length. The bagworm is one of the first discussed. This worm "lives in and carries about with it a case made of silk, on the outside of which it fastens bits of leaves, probably to render its detection less easy to birds and other enemies. One may see these cases all through the winter adhering to the naked twigs of both deciduous and evergreen trees, the worms having taken the precaution to fasten. them there by wrapping the twigs with silk. The case of a grown worm measures 1.75 inch in length and its greatest diameter is some'Edited by Clarence M. Weed, New Hampshire College, Durham, N. H.

2 Bulletin No. 47, Kentucky Agr. Experiment Station.

what more than .50 inch. large number will be found empty, these being old ones which adhere to the twigs longer than one season, or else are those which produced males. In every one which produced a female the preceding summer will be found an oblong brown cylindrical object tapering a little at one extremity, but blunt and with a ragged opening at the opposite end through which the adult insect escaped; for these are the deserted pupal skins of the female. Each appears, at first to be full of a powdery material, but on removing some of this the minute soft whitish eggs will be observed packed closely so as to fill the greater part of the skin.

If cases are examined during the winter a

The bag-worm. a, larva; b, pupa; c, adult female; d, adult male; e, bag containing eggs; f, bag containing larva; g, young larvæ, with conical cases. (From Riley).

"The adult female of the bag-worm is a very singular creature, looking more like a worm than a moth, incapable of flight, having no rudiments of wings, and with only minute and functionless legs. The very scales of the greater part of her body are abortive, and are rubbed off to constitute the powdery material in which the eggs are packed. Being incapable of flight the most she can do is to wriggle down to the opening at the lower end of her case where she meets the winged mate, and then in the same manner wriggles back to her empty pupa case in which she carefully placed her eggs for safe-keeping during the winter. Finally with an astonishing solicitude for the walfare of her prospective young, she deserts the case, drops to the ground, and dies shortly afterward. Is it possible that this pulpy mass, exhausted, with nothing more to live for, with death certain and at hand, understands

that a dead and putrid body left in the case would work harm to her precious eggs? Anyway she leaves the case."

Mr. Garman photographed a member of the cases from different trees, as shown on the accompanying plate. Those marked a are from red cedar; b, from maple; c, from arbor vitæ ; d, from spruce; and e from white pinė.

An extended account of the elm borer (Saperda tridentata) is also given. This insect had done serious

injury to some of the largest and finest elms in the city of Frankfort. The nature of the damage is well-shown in the plate reproduced herewith. Washing the bark with a mixture of whitewash and Paris green is suggested as a preventive measure.

Eim-borer: larva and adult.

Larval Habits of Brachinus.-Mr. H. F. Wickham records (in the Canadian Entomologist) finding in northern Iowa the larvæ of a species of Brachinus parasitic on the pupae of Dineutes assimilis. "The larva lies in the cell of its host and extracts the juices from an opening made in one of the wing-pads; the maggot-like body is adorned, but not supported by six very soft and short legs, which can be of little service except perhaps as 'feelers' in its dark abode. The little animals were carefully watched and examined several times a day, until finally the larger one, having withdrawn nearly all the juices from the pupa and become swollen to an unwieldy size, changed after a day or two of resting into a pupa.

"How the Brachinus gets into the cell of it host, whether brought in as a young larva clinging to that of the Dineutes, or deposited as an egg by the mother is a mystery to me. When small it is more active than when larger grown, and with advanced age becomes gradually more helpless. In any case the complete adaptation to a parasitic habit is apparent in the whole structure-the soft, juicy body, unprotected by chitinous scutes, the weak legs quite useless for ambulatory purposes, and the lack of strong locomotive bristles. The appearance is almost that of some Hymenopteron, not at all resembling the strong raptoreal larvæ of the Adephaga in general."

North American Trypetidæ.-Mr. W. A. Snow makes an important addition to our knowledge of a little-studied family of Diptera

in his descriptions of North American Trypetida, with notes. Good descriptions of a large number of new species are published, together with valuable notes on the distribution of those already known. Two new genera-Polymorphomyia and Xenochaeta-are characterized. Two plates illustrate the wing markings of many species.

North American Dolichopodidæ.-Professor J. M. Aldrich in his New Genera and Species of Dolichopodidae describes five new species, and characterizes two new genera-Dactylomyia and Metapelastoneurus. He also gives a table of the species of Sympycnus.

Entomological Notes.-At a recent meeting of the Entomological Society of London Mr. S. H. Scudder "exhibited the type-specimen of a fossil butterfly-Prodryas persephone-found in beds of Tertiary Age at Florissant, Colorado. He said the species belonged to Nymphalidæ, and the specimen was remarkable as being in more perfect condition than any fossil butterfly from the European Tertiaries. He also said

that he had found a bed near the White River on the borders of Utah in which insects were even more abundant than in the Florissant beds." K. T. Nogakushi of the Imperial University, Tokio, publishes a preliminary notice of his investigations of the Spermatogenesis of Bombyx mori. The author distinguishes four zones in the follicles: the formative, growing, ripening, and that of metamorphosis.

At a recent London sale a specimen of Chrysophanus dispar sold for six pounds, ten shillings; and a pair of Noctua subrosea for six pounds. six shillings.

In his report as Dominion Entomologist for 1893, Mr. James Fletcher discusses a large number of injurious insects affecting various Canadian Crops.

* Kansas University Quarterly, II, 159-174; Jan., 1894.

L. c. 151--157.

5 Ent. Mon. Mag., V, 22.

Zool. Anzeiger, XVII, 20.