350 Agassiz on the Embryology of the Turtle. 
is inclosed ; and I suspect that a kind of Graafian follicle, which in many 
animals drops from the ovary with the egg, has frequently been mistaken 
for a vitelline membrane. I believe, further, that the scar resulting from 
the separation of that follicle forms the opening called micropyle, and 
that this opening does not traverse the vitelline membrane. In Turtl 
of the view of those who would ascribe its superficial position to the in- 
fluence of fecundation. It is formed in that position, and preserves it as 
long as it exists.”—pp. 489-492 
Egg Laying.—By careful comparisons, it has been possible to 
ascertain at what age at least one species begins to lay its eggs 
and reproduce its kind. Chrysemys (Emys) picta does not lay 
its eggs before the eleventh year. With other turtles the data 
were not so complete, but in all probability they may be said to 
lay their eggs from the eleventh to the fourteenth year, accord- 
ing to the species. They all do this too in the spring, in the 
month of June, both at the north and south; physical differ- 
ences not seeming to have the least effect upon this particular 
function. 
The formation of Albumen.—The mode of formation of the 
albumen is very different from what it is among birds, there be- 
ing no chalazse nor spiral arrangement of the layers. The shel 
and albumen are both deposited at the posterior end of the ov 
duct, and the albumen is not applied against the surface of the 
yolk by direct contact of the inner surface of the oviduct, but 
im a great measure infiltrates through the previously form 
shell membrane. 
The albumen is composed of innumerable layers of amorphous 
substance, in which are imbedded a multitude of elongate, oval, 
coarse, granular bodies pointing in a particular direction 1D each 
layer, some along the longer axis of the egg, some across the 
same, and others in intermediate directions between these two- 
The shell membrane-—This arrangement is carried out 1m 
beautiful manner in the shell membrane whose inner ae ae 
ie) ? 
r the manner of the albumen and the shell membrane. ae 
Shell is composed of characteristic groups of carbonate arr 
more or less intimately soldered together side by side, 
