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N 
74 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. 
Table III 
Tabulation of Hıs’ correlation of a series of Pristiurus embryos with BALFOUR’s stages 
and of a set of measurements of the former. 
Hıs’ series 
Bir Länge des Breite des Breite des Ban sen 
Hufeisens Hufeisens Vorderkopfes vorn gemessen 
I 0.4 mm. 0.55 mm. — u 
2 05, 05% — 0.25 mm. B 
3 8,7 05 (Ca = O28 =, 
4 OB Oran — 0280, 
5 RO 9.05, 5 0.62 mm. 0:28 055, C 
6 DET 0 G:0200,, _ h 
7 1.14 „ 0.33» 075 5 En ' D 
8 1.6 = OR O7, — 
9 280. 00%, oa O7 —_ E 
A second part of the same paper contains descriptions and reconstructions, plastic and graphic, 
of embryos corresponding to BALFOUR’s stages “C”, “D”, beginning of “E”, end of “E” and “F”. 
These have been placed under “B” in the column devoted to this paper in the normal plate table. 
The stages reconstructed by Hıs concur closely with those of BALFOUR bearing the same designation, 
with the exception of “F”. Of this he says: “Zur Stufe “F” rechne ich gleich den Gebr. ZIEGLER solche 
Embryonen, bei denen das Markrohr schon großenteils geschlossen ist... .” The embryo reconstructed is 
one of Seyllium canicula, of 13 or more segments, and seems to be more comparable with BaLrour’s “G”. 
EMMERT, in 1900!) (Table IX, column ı1), published an account of four young embryos of Torpedo 
marmorata. The anatomy of each specimen is briefly described and is illustrated by cross sections. In 
addition to the account of the general anatomy there is a more detailed description. The external 
appearance of the series is illustrated by photogravures of each specimen as seen from above. The 
author carefully correlates his specimens with the ZIEGLER’s modification of the BALFOUR series. This 
correlation is presented below in tabular form. 
Table IV. 
Tabulation of EMMERT’s correlation of his series of embryos of Torpedo marmorata 
with the “BALFOUR-ZIEGLER” stages. 
EMMERT’s series 
“BALFOUR-ZIEGLER” stages 
Stadium Length Number of segments 
I 2.3 mm. 10 D 
II E= 22 F 
DI 3.2 mm. 16 F—-G 
IV — — H 
Besides the LEypıc’s contribution, which has already been considered, four other papers dealing 
exclusively with Squalus acanthias have been tabulated. 
Locy’s preliminary paper?) upon the medullary plate and groove (Table IX, column 8), contains 
brief discussions of a number of the main characters of early embryos of Squalus. The period covered 
I) J- EMMERT (1900), Beiträge zur Entwicklungsgeschichte der Selachier, insbesondere nach Untersuchungen an jüngeren 
Embryonen von Torpedo marmorata. Arch. f. mikr. Anat., Bd. 56, p. 459—487, 38 figs., Taf. XX. 
2) W. A. Locy (1893), The formation of the medullary groove and some other features of embryonic development in 
elasmobranchs. Journ. Morph., Vol. 8, p. 367—378, pl. XIX, 
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