THE EARLY DEVELOPMENT OF AMIA, 421 
II. Toe Earty DeveLorMEnT or AMIA. 
A. The Egg and Egg Membranes.—Theegg, shortly after 
its deposition (15’—80”), presents the general appearance of 
P1.30, fig.1. It has assumed an oblong form, averaging 2°2 x 2°8 
mm. The germinal area, even in freshly deposited eggs, was well 
defined as a whitish cap reaching down to about one third of 
the ege’s longer or vertical axis. Its yolk pole region is pale 
greyish in colour (resembling that of the freshly laid sturgeon 
egg), and retains this colour throughout earlier development, 
appearing dingier and browner, however, as the outer mem- 
branes become soiled. 
A single micropyle probably occurs, as in Lepidosteus and 
the Teleosts. Of this, however, the writer is by no means sure, 
as his only observation was made hastily during a collecting 
trip, and he neglected to immediately harden his material. 
The egg membranes are essentially similar to those of Lepi- 
dosteus and Acipenser ; they appear, however, relatively thin- 
ner and more intimately associated with the egg. They are 
not to be removed by needles until the embryo has become 
well established ; even then the process isa difficult one. There 
is present a well-marked zona radiata and villous layer; these, 
in the younger stages, are approximately of equal thickness. 
The radiata is more compact in structure than in the other 
Ganoids; the villous layer, on the other hand, is of a far 
looser texture, its elements crumpled and intertwined, the 
heads of the villi oblong and swollen. At the point of the egg’s 
attachment, e. g. the stem of waterweed, furthermore, as may be 
seen in the adjoining figure (Fig. 4), the villi become enormously 
elongated, their heads firmly fixed to the attaching object. A. 
granulosa occurs irregularly ; it sometimes appears as a cell 
tract of considerable size, at other times it is almost wanting ; 
it has certainly no such important relation asin Acipenser. In 
Pl. 30, fig. 1, the egg is shown attached to the waterweed ; its 
membranes show a broad jelly-like base consisting of the elon- 
gated villi, and the mottling roughnesses of the egg surface re- 
present patches of the granulosa. 
