Page:Proceedings of the Royal Society of London Vol 60.djvu/502

468 In fig’. 1 an egg is represented as seen in its nsual natural attached position The depressed or “ anterior ” end of the egg is, as a rule, directed vertically upwards. The outer capsule is continued in front into two thin, translucent, terminal processes. For nearly half the length of the egg on the upper side the two halves of the outer capsule are separated by a narrow slit from one another and join together behind the centre of the egg. The dorsal ridge or suture of the inner capsule can be seen through this slit in the outer capsule. On the lower side of the egg the two halves of the outer capsule are continuous across the middle line throughout the length of the egg, except at the extreme anterior end.

The surface of the egg in the posterior inflated region is smooth, with a few slight folds like the folds of drapery, giving it a graceful

F ia 1 —Fertilised egg of Nautilus macromphalus in the natural attached Position. The pectinate ridges and fenestrations, together with the slit m the wall of the outer capsule, are well seen. The arcuate thickening m the middle of the posterior half of the egg is due to the fusion of the outer with the inner capsule. In this ovum the anterior membranous prolongations of the outer capsule were unequal, the larger of them having the form of a thin flattened expansion.

Fm 2 _The same egg from the side, showing the inflated posterior or proximal i w i T t o L a to n e d distal portion, a. also the spongy area of attachment.