468 



Dr. A. Willey. 



In fig. 1 an egg is represented as seen in its usual 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 cap- 

 sule 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 onter capsule. On 

 the lower side of the egg the two halves of the outer capsule are con- 

 tinuous 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 



FiG. 1. Fertilised egg of Nautilus macromphalus in the natural attached position. 

 The pectinate ridges and fenestrations, together with the slit in the wall of the 

 outer capsule, are well seen. The arcuate thickening in 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. 



FiG. 2. The same egg from the side, showing the inflated posterior or proximal 

 portion and the more flattened distal portion, as also the spongy area of 

 attachment. 



