Embryology. l 863 
st likewise, in this instance, be so considered. This type is 
only vertebrate yet examined which possesses eight distinct 
endages which may be legitimately considered as represent- 
four pairs of limbs. 
tis a singular ciréumstance that the ventral fin-folds in the 
: embryos described by Mr. Watase are not double in the region 
tbe anus. In every other respect these remarkable forms 
mish confirmation of Dohrn’s view as to the nature of the 
Median ventral fin-fold of fishes. 
Mr. Watase describes four principal types or modifications of 
_ le development of the paired fins of these interesting fishes. 
Upon the whole, his memoir is one of the most interesting in its 
mags upon morphology of the limbs of fishes which has ap- 
, Peared for many years.— Fohn A. Ryder. 
en Inversion of the Germinal Layers in Hesperomys.— 
mng the past summer the writer has succeeded in obtaining 
Ome 
OO 
SERN 
Or 
DUD: 
Sa 
ZOONS 
“on, ¢, enters directly into. the formation T 4. -a 
embryo, a is seen the amniotic part | gee Rp a! FS : 
Cavity enclosed by the epiblast, and at f f ay Eis iar 
cavity, which at a later period is yes al Bye 
the cavity of the amnion. The ERST ‘ 
the blastosphere at one end by essere Sauk 
l a ‘sphere so as to obliterate the cavity of the yelk-sac, as 
the other genera named, T y 
