Page:Proceedings of the Royal Society of London Vol 60.djvu/503

Rh F ig. 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 num ber of pectinate ridges and of fenestrations in the wall of the outer capsule (figs. 1—3). Sometimes, however, the pectinations are obscure and the fenestrations may be absent.

H ardly will any two eggs present an exactly sim ilar 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 w ith 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 w ith anterior pointed extrem ity and a generally smooth surface. Its wall has a finely striated structure, the striae having a w atery appearance. There aie 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 prom inent ridge which is produced in front beyond the anterior extrem ity of the main body of the inner capsule into a slender term inal appendix.

The lateral sutures are marked by less prom inent ridges, and are continued into one another anteriorly, immediately behind the anterior extrem ity of the inner capsule. In consequence of the continuity 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