200L0QY AND BOTANY. MICROSCOPY, ETC. 
279 
Embryonic Shell of Bivalves.* * * § — M. Felix Bernard describes the em- 
bryonic shell or “ prodissoconque ” in a number of Lamellibranch types. 
The stage which shows it is well marked, it is a period of rapid embryonic 
growth and differentiation, it is terminated by a short period of arrest. 
He argues that the larva with the prodissoconque represents an ancestral 
type — with its two adductors, its pedal muscles, its three pairs of ganglia, 
its creeping foot, its mantle with free lobes and no siphon, its gills 
situated far back, its velum, and so on. Antecedent to the prodissoconch 
is the protostracum without cardinal differentiation, as seen in the 
Glochidium larva ; this earliest stage he has succeeded in demonstrating 
at the apex of all the prodissoconques studied. 
Arthropoda. 
Appendages of Arthropods.f — Herr A. Jaworowski returns to his 
theory that Arthropod appendages [and gills in Crustacea] are refer- 
able phylogenetically to respiratory insinkings of the skin. Anatomical, 
developmental, and pathological facts all seem to him to point to the 
conclusion that mouth-parts, limbs, wings of insects, eye-stalks of Crus- 
tacea, &c., are referable to primitive folded lung-like insinkings of the 
skin. His arguments do not appear to us in any way conclusive, but 
they are of the sort often used in speculative phylogenetic studies, and 
are nothing if not ingenious. They lead him to renewed confidence in 
the unity of the Arthropod Ur stamm. 
a. Insecta. 
Aquatic Insects of the Illinois River .J — Mr. C. A. Hart publishes 
the first paper of a memoir on the insect fauna of the Illinois River and 
adjacent waters. It is designed partly as a basis for further work, and 
partly for the use of Illinois students. It is admirably conceived as a 
faunistic guide, giving prominence to the nutritive and other bionomical 
relations of the forms described, and to their life throughout the year. 
Myasis of Alimentary Canal in Man.§ — Dr. P. Lallier has pub- 
lished his thesis on this subject. He has compiled a very complete record 
on the subject, and furnishes a useful bibliography. There is no doubt 
that larvae of Antliomyia, Sarcophaga, Musca, Calliphora, Teichomyza, &c,, 
may live for some time in the food-canal of man. The author discusses 
their introduction, effects, and distribution, and the medicinal treatment 
of cases. 
Viviparity in Ephemerids.|| — Dr. R. Heymons directs attention to 
M. Causard’s IT observation of viviparity in Cloeopsis diptera Latr., and 
points out that von Siebold noted the viviparous birth of an Ephemerid 
in 1837, and Calori (in Cloeon dipterurn) in 1841. Causard’s observation 
is very welcome, but not altogether novel. Heymons notes further that 
viviparity may be more frequent in southern regions, for Cloeon dipterurn 
is demonstrably oviparous in Berlin. 
* Comptes Rendus, exxiv. (1897) pp. 1165-8. 
f Zool. Anzeig., xx. (1897) pp. 177-84 (3 figs.). 
X Bull. Illinois Lab. Nat. Hist., iv. (1897) pp. 149-284 (15 pis.). 
§ ‘Etude sur la My asedu tube digestif cliez rhomme.’ These. 8vo, Paris, 1897, 
120 pp., 1 pi. || Zool. Anzeig., xx. (1897) pp. 205-6. 
t Comptes Rendus, cxxiii. (1896) p. 705. 
U 2 
