342 
existence as yet of sex-differentiation, the acquisition of these two in 
Lepidosteus being apparently deferred. 
An examination of the history of the merocytes in Lepidosteus 
possesses a priori enhanced interest, because, by many at least, the 
mode of segmentation of the egg has been regarded as intermediate 
in type between those of Elasmobranchs and Amphibians. BALFOUR 
and PARKER!) first showed that some furrows of the segmentation 
cut the lower hemisphere of the egg, and, thus, that the latter belongs 
to those classified as holoblastic. They remark (p. 362): — “we have 
observed several stages in the segmentation, which show that it is 
complete, but that it approaches the meroblastic type more nearly 
than in the case of any other known holoblastic ovum”’. 
My own work led me to confirm this conclusion, and in a pre- 
liminary paper I wrote as follows: — “the segmentation is very unequal 
but in a sense complete. FEight furrows can be traced to the 
centre of the lower pole. The attempt to segment the lower hemi- 
sphere is, however, soon given up, none of the eight furrows penetrate 
very deeply into the yolk, and none reach the centre by a long way. 
They are only superficial furrows.” 
In a recent publication BASHFORD DEAN?) has practically chal- 
lenged the accuracy of these results, and from his own studies is in- 
clined to conclude that the appearances described by previous investi- 
gators are exceptional and occasional, his own examination of a great 
number of eggs having taught him that the segmentation is quite of 
the meroblastic kind *). 
Personally, it would be to me a matter of complete indifference, 
to which kind of segmentation Lepidosteus belonged, but differences 
in modes of segmentation do, as I think can be demonstrated, furnish 
some indication of variations in the modes of larval development, and, 
hence, may be of assistance to the investigator in search of the larval 
1) F. M. Barrour, and W. N. Parker, On the structure and de- 
velopment of Lepidosteus. Phil. Trans. London, 1882. 
2) Basurorp Dean, The early development of Gar-pike and Sturgeon. 
Journ. of Morph., Vol. XI, p. 1-—56. With 4 plates. 
3) More recently still, Dean (Q. J. Microsc. Se., Vol. XX XVIII, p. 425) 
has recorded a similar conclusion for Amia. Until this discovery be confirmed 
by observation on eggs of Amia preserved with Fremmine’s mixture, or 
with some other combination of osmic acid, it will not be above the sus- 
picion of being inaccurate, for Dran may as easily have been deceived 
by his reagents in this case as in that of Lepidosteus. Compare, also, 
H. Vırcmow and Sozorra, Verhandl. Anat. Gesellsch. Berlin 1896, p. 108 
—111. 
