276 THE OVARIAN EGG. 
indeed, in all eggs, but in those which produce 
but one individual is only a stage in the natural 
growth of the yolk during its transformation into 
a young embryo. As the facts here alluded to 
are not very familiar, even to professional natural- 
ists, I may be permitted to describe them more 
in detail. 
No one who has often walked across a sand- 
beach in summer can have failed to remark what 
the children call ‘‘sand saucers.” The name is 
not a bad one, with the exception that the saucer 
lacks a bottom; but the form of these circular 
bands of sand is certainly very like a saucer with 
the bottom knocked out. Hold one of them 
against the light and you will see that it is com- 
posed of countless transparent spheres, each of 
the size of a small pin’s head. These are the 
eggs of our common Natica or Sea-Snail. Any 
one who remembers the outline of this shell will 
easily understand the process by which its eggs 
are left lying on the beach in the form I have 
described. They are laid in the shape of a broad, 
short ribbon, pressed between the mantle of the 
animal and its shell, and, passing out, they cover 
the exterior ef the shell, over which they are 
rolled up, with a kind of glutinous envelope, — 
for the eggs are held together by a soft gluti- 
nous substance. Thus surrounded, the Natica, 
whose habit is to burrow under the surface of 
