The Oviposition of Nautilus macrompkalus. 469 



FIGK 3. The same egg as in the preceding figures, from below. Behind is the 

 somewhat irregularly shaped spongy area of attachment. 



appearance. The anterior depressed region is characterised by the 

 presence of a number of pectinate ridges and of fenesirations in the 

 wall of the outer capsule (figs. 1 3). Sometimes, however, the pec- 

 tinations are obscure and the fenestrations may be absent. 



Hardly will any two eggs present an exactly similar appearance. 

 Sometimes there are shred-like processes from the surface of the 

 outer capsule, lending a more or less tattered appearance to the egg. 



In fig. 4 another egg is shown with the above-described slit in the 

 upper wall of the outer capsule, widened out so as to disclose the 

 inner capsule to view. 



The inner capsule has a regular oval shape with anterior pointed 

 extremity and a generally smooth surface. Its wall has a finely 

 striated structure, the striae having a watery appearance. There are 

 three distinct seams or sutures, representing lines of least resistance, 

 in the wall of the inner capsule, namely, a median suture on the 

 upper side (i.e., the side directed away from the attached side of the 

 egg), and two lateral sutures placed towards the lower surface of the 

 capsule (figs. 4 6). 



The dorsal suture is marked by a prominent ridge which is pro- 

 duced in front beyond the anterior extremity of the main body of 

 the inner capsule into a slender terminal appendix. 



The lateral sutures are marked by less prominent ridges, and are 

 continued into one another anteriorly, immediately behind the 

 anterior extremity of the inner capsule. In consequence of the con- 

 tinuity of the lateral sutures, the lower side of the egg can be raised 

 up like a cap or an operculum. The inner capsule is often easily 



