26 G. O. Sars. 
Seen from the side (fig. 1), the shell exhibits a rather 
regular ovoid form, with the greatest height about equalling 
3/5 of the length, and occurring behind the middle. The 
anterior extremity is somewhat produced and truncated at 
the end from the front backwards, a circumstance very seldom 
found in the Cyprididæ. The posterior extremity is much 
shorter, and obtusely rounded at the tip. The dorsal mar- 
gin forms a bold and rather regular curve, having its highest 
point considerably behind the middle. Thence it slopes 
quite gently towards the front edge, whereas behind it 
curves more steeply to the posterior extremity. The ventral 
margin does not exhibit any median sinus, but is, on the 
contrary slightly convex, in the middle. It joins the anterior 
and posterior edges without any intervening angle. 
Seen from above (fig. 2), the shell appears rather more 
tumid than in the other 2 Australian species, the greatest 
width, which occurs considerably behind the middle, almost 
attaining half the length. Both extremities appear obtusely 
pointed, but the anterior one is much narrower than the 
posterior and slightly twisted at the tip. 
The valves, as in the other species of the genus, are 
rather unequal, the right one being conspicuously more con- 
vex than the left, and overlapping it at both extremities 
by a thin hyaline border, which, especially on the anterior 
extremity, is rather broad. Ventrally also, the left valve is 
found to overlap the right considerably, and this is the reason 
why the usual ventral sinus does not appear in the lateral 
aspect of the shell. On the other hand, the right valve 
projects dorsally to some extent beyond the left one in a 
manner similar to that found in C. cingalensis. On view- 
ing the shell from the left side (fig. 1), therefore, a part of 
this valve is seen raised above the hinge, though not form- 
