GENUS TROPIDOLEPTUS. 



279 



XII. ON THE GENERA TEREBRATULA, CENTRONELLA, CRYPTO- 



NELLA, ETC. 



This paper will be deferred to the next Report on the State Cabinet, on 

 account of the non-completion of the illustrations designed to accompany it. 



XIII. ON THE GENUS TROPIDOLEPTUS.* 



The Genus Tropidoleptus was proposed by me in the 10th Report on 

 the State Cabinet, published in 1857. The shell made the type of the 

 genus was the Strophomena carinata, Conrad, published in the Annual 

 Report on the Palaeontology of the State for 1859. At the time of propo- 

 sing this generic name, very little was known of the interior structure of 

 the shell, and it was separated on account of hinge structure and the 

 punctate texture of the shell. 



The accompanying figures will give a general idea of the form and exte- 

 rior character of the T. carinatus : 



Fig. 1. Fig. 2. 



1 ^^-.ia^ 2 



Tropidoleptus carinatus: Tropidoleptus carinatus: 



Dorsal view. The surface is partially Ventral view, 



covered by a delicate bryozoan. 



In 1850, I had obtained some further knowledge of the interior, as 

 shown in figs. 3 and 4. 



Fig. 3. Fig. 4. 



ft 



Fig. 3. The interior of the ventral valve, showing the area, foramen, teeth, etc., 



enlarged. 

 Fig. 4. The interior of the dorsal valve, showing the cardinal process, the dental 



fossets, the bases of the crura, and the septum. 



* This paper was communicated to the Nineteenth Report on the State Cabinet, but not 

 printed. The Notice of Vol. iv, Palaeontology of New-York, published in the present 

 Keport, in which the observations on this genus are cited, causes some unavoidable repe- 

 tition. 



