388 The American Naturalist. ‘[April, 
ZOOLOGY. 
= The German Zoological Society.—The annual report of this 
society for 1892 is out, and contains among others the following 
The opening address by the President, Professor F. E. 
Schultze, described the zoological department of the University of 
Berlin, where the meeting was held, giving also a sketch of its history. 
Professor H. E. Ziegler spoke upon the embryonal anlage of the blood 
in the vertebrates. At first the blood is a clear serum in which no 
corpuscles appear. Later they are present. Various ideas have been 
advanced as to their origin. Ziegler vigorously discusses the view 
which assigns them to the entoderm and decides that they are without — 
doubt mesodermal in origin. Dr. L. Plate described the anatomy and 
affinities of the Onchidiide. These forms belong to the Asiatic region, 
and are amphibious, living equally well in or out of the salt water. 
To separate the genera the author uses the relative width of the foot 
and of that suprapedal region to which he gives the name of hypono- 
tum. The group is of great interest from the fact that though usually 
regarded as Opisthobranchs they must be considered as near the 
ancestral Pulmonate. Plate, however, thinks that they have crossed 
the line and are true Pulmonates, but that their Nudibranch charac- 
ters are such as cannot be explained except upon the hypothesis of 
descent from that group. Dr. Thiele, in discussing the phylogeny of 
the byssus apparatus of the Lamellibranchs, thinks that it must be 
traced back to some such type as the adhesive glands of Haliotis, and 
does not agree with Pelseneer in regarding the byssal glands of the 
Nuculide as the most primitive. The fact that either in young or in 
adult the byssus occurs in most Acephals, is proof to Thiele that the 
gland must be traced back to the ancestral mollusc. Von Nathusius 
discussed the form and color of the hair as a basis of classification of 
the Equidæ. Dr. Korschelt presented a paper on the differentiation 
of the germ-layers in the Cephalopods with especial reference to the 
formation of the alimentary canal and the nervous system. Accord- 
ing to Bobretzky both the midgut and the nervous system are of meso- 
dermal origin, while several other authors think that the whole 
alimentary canal is formed by ectodermal inpushings (stomo- and proc- 
todeum). Korschelt finds' that at an early date an epithelial layer 
arises just above the yolk in the anal region. It is distinctly separa 
1The full paper with illustrations appears in the Leuckart Festschrift. 
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