UTHOTRYA NICOBARICA. 361 



near the bottom of tins margin, there is a very slight pro- 

 jection, answering to the small knob at the baso-tergal 

 angle of the scutum. Externally, towards the basal angle, 

 the narrow strip not concealed by the overlapping of 

 the latera and carina is square-edged, with the zones of 

 growth on it straight. 



. Carina, internally concave in the upper free part, with 

 a slight, central, internal crest, caused by the projection 

 of each successive zone of growth. The inner growing 

 surface is almost pentagonal in outline ; with the basal 

 margin square and truncated in the middle. 



Bostrum (fig. 2 a), rather conspicuous, many zones of 

 growth being preserved. It equals in width six of the 

 subjacent scales of the peduncle, but as these are rather 

 smaller than elsewhere, the width equals about five of the 

 ordinary uppermost scales ; compared with the latera, it 

 is nearly fths of their width. 



Latera, unusually large ; as seen on their interior sur- 

 faces, (or in a section parallel to the zones of growth,) 

 they are triangular, elongated transversely, with the 

 carinal angle a rectangle. In width they equal the seven 

 subjacent scales of the peduncle, and are more than half 

 as long as the basal margin of the carina. 

 , Peduncle, with the upper scales varying from circular 

 to quadrilateral, thrice as large as those in the second 

 whorl ; beneath which, in the next three or four whorls, 

 the scales rapidly decrease in size ; and beneath these the 

 whole peduncle is studded with equal-sized, rounded, cal 

 careous beads, so minute as to be quite invisible to the 

 naked eye. This specimen was, nearly ready to moult, 

 and perhaps in consequence of this, even the upper scales 

 were most obscurely serrated on their lower margins, and 

 all the others quite smooth : there were some much worn 

 horny spines c close to the bottom of the peduncle. Basal 

 calcareous cup slightly concave, of moderate size ; its dia- 

 meter, in the one specimen examined, was ^ths of an 

 inch ; it was composed of several layers. In the specimen 

 figured (2 a') by Reinhardt, instead of a cup, there is a 



