EMBRYOLOGY. 
Moll 1.‘3 
Note on the germinal vesicle in Mollusca^ by S. Trinchese, Mem. Acc. 
Bologn. (3) vii. p. 4G3. 
W. K. Brooks compares the embryonal stage of the Mollusca^ provided 
with a ciliated veil, which he calls Veliger^ with the Pohjzoa, especially 
those which bear a lophophore, and regards Dentalium as the lowest 
among the Mollusks, from which Bivalves and Gastropods are to be 
deduced. P. Bost. Soc. xviii. [1876] pp. 225-236. 
The first changes in the egg of Neritina fluviatilis, and the develop- 
ment of Paludina vivipara \^Listeri] have been observed by O. Butschli, 
in the latter also the original orifice of the Gastrula becomes the vent of 
the adult animal ; to this stage succeeds one called “ Trochosphvra,^' yjiih 
a ring-liko girdle of cilia round the midst of the body. Byes and 
otocysts have their origin in an invaginatod part of the ectoderm. Z. 
wiss, Zool. xxix. pp. 216-239, pi. xv.-xvii. 
The segmentation of the yelk, and the part which the germinal vesicle 
takes in it, observed in Limncea stagnalis and Anodonta^ by A. Brandt, 
op. cit. xxviii. pp. 586-606, pi. xxvii. 
Egg of Facelina drummondi (Aid. & Hanc,), fam. MoUdidcc, microscopi- 
cally described by S. Trinchese, Rend. Acc. Bologn. 1877, May, 12 pp. 1 pi. 
The formation of the egg in Scrohicularia piperata is described by 
H. VON IiiERiNG, Z. wiss. Zool. xxix. pp. 1-14, pi. i. He comes to the 
conclusion that in Bivalves the membranes of the egg are produced by 
the egg itself. 
E. R. Lank ESTER, in a general paper on the embryogeny and classifica- 
tion of the animal kingdom, recapitulates his observations and views as to 
the embryology of many Mollusca ; and gives a sketch of a new classifi- 
cation in which the Mollusca are derived directly from the Gcpliyrea, 
and placed as usual between the Articulata and Vertehraia ; they are sub- 
divided, partly in accordance with Ihering’s views, as follows ; — 
Branch A. — Encephala [C^phal^s, Lam.] 
Grade A. — Lipoglossa, Class Scolecomorpha, gen. Neomenia. 
Grade B. — Echinoglossa, Class I., Gastropoda ; II., Cephalopoda, 
including the Pteropods ; and III., 
Bcaphopoda (Dentalium). 
The Gastropods are thus subdivided: — 
Grade a . — Amphineura. Order. — Polyplacophora (Blainv.), Chiton 
and Chitonellus. 
Grade h. — Cochlides. Ord. 1. — Autocochlides [Prosobranchia], 
Patella and Buccinum. 
Ord. 2 — Natan tia [Heteropoda], Atlanta 
and Pterotrachea. 
Ord. 3. — Cry ptocochl ides [Opisthobran- 
chia], Aphjsia and Eolis. 
Ord. 4. — Pulmouata [Cuv.], Limax and 
Limnoia. 
Branch B.— Lipocephala [Acephala, Cuv.]. 
Class I., Tentaculibranchia (Bryozoa) ; II., Spirobranchia (Bra- 
chiopoda) ; III., Lamellibranchia. 
Q. J. Micr. Sci. xvii. pp. 448 & 449. 
