Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. 
Table VI 
Tabulation of JOHNSTOnN’s correlation of a series of Squalus acanthias 
embryos with BALFOUR’s stages. 
JOHNSTON’s specimens 
BALFOUR’s stages 
Fig. Number of segments 
G 
16 H 
15—17 I 
18 late K 
Two comparatively recent works have appeared dealing with the embryology of the Chimaeroid fishes: 
SCHAUINSLAND’s on COallorhynchus and DEAN’s on Chimaera colliei. 
SCHAUINSLAND!) (Table IX, column 12) figures a series of embryos, two of which are inter- 
mediate between BaLrour’s “A” and “B”. The normal plate 2 and others corresponding roughly to 
BAaLFour’s “G”, “HA”, “I”, “K”, “L” and “O”. No description is given of the anatomy as a whole of 
this series but the gastrulation, and development of the skin, cranial nerves, teeth and extremities are 
considered. 
Dean’s?) (Table IX, column 13) paper on Chimaeroid fishes is to a large extent a description of 
the development of Chimaera colliei. The egg and eggenvelopes, fertilization, segmentation, and gastrulation, 
are described in detail, and the general features of stages corresponding to BALFoUR’s “D”, “E”, “F” and 
“G”, are described and illustrated by series of sections. Of the later stages, only notes on the skull, gill 
slits, and extremities, are given, although mention is made of the condition of the central nervous system, 
pronephros, eye and digestive tract. The contribution includes an extensive series of figures, — the most 
complete yet published of elasmobranch embryos, — from the unsegmented blastoderm to the adult fish. 
A number of the embryos figured are correlated by the author with BaLrour’s stages. This correlation is 
given below in tabular form. 
ee VAnE 
Tabulation of DEAn’s correlation of Chimaera colliei embryos with stages 
of BALFOUR’Ss series. 
DEAN’s specimens 
BALFOUR’s stages 
Figure Age in days 
34 B 
35 “Jate B” 
36, 40 
37, 41 
38, qIa, 4Ib 
42, 42a, 42b 
43, 432, 43b 
44 
45 
46 “Somewhat older than L” 
49 130 N 
50 180 12 
1) 1903, H. SCHAUINSLAND, Beiträge zur Entwickelungsgeschichte und Anatomie der Wirbeltiere, I. Zoologica, Bd. 39. 
2) 1906, B. DEAn, Chimaeroid fishes and their development. Carnegie Institution of Washington, Publ. No. 32, 194 pp- 
ıı pls., 144 figs. 
