274 



NOKTH-CAEOLINA GEOLOGICAL 8UKVEY. 



CLASS BKACHIOPODA. 



FIG. 187. 



ORBICULA LUGUBEIS. CON. (Fig. 187.) 



Shell corneous, oblong-ovate, depressed ; 

 concentrically lamellose ; apex behind the 

 centre ; posteriorly, it is marked by a few 

 radiating lines; interiorly, it is smooth, 

 and there is a short longitudinal ridge on 

 the median line. In some of the miocene 

 beds in Wayne county, it is quite common. 



FAMILY DENTALLDAE. TOOTH SHELLS. 



The dentalidae are hollow, curved tooth-like shells. They 

 are usually ornamented by longitudinal ridges, but sometimes 

 they are smooth and polished. They have a round or circular 

 aperture. 



DENTALUM ATTENUATUM. SAY. (Fig. 188.) 



Shell gently curved, and ornamented 

 with twelve rounded ribs ; aperture cir- 

 cular. Common in the shell marl of this 

 State. 



FIG. 188. 



D. THALLUS. CON. (Fig. 189.) 



Shell small, polished, curved and ta- 

 pering towards both extremities. Com- 

 mon in the shell marl. 



FIG. 190. 



FIG. 189. 



CAECUM ANNULATUM. N. 8. (Fig. 190.) 



Shell minute curved ; ends subequal ; 

 aperture circular ; surface annulated. 



This minute shell is quite common in the miocene of this 

 State. It is found in the interior of larger ones, which it 

 probably inhabited. 



FAMILY CALYPTKAEIDAE. LIMPETS. BONNET LIMPETS CUP AND 



SAUCER LIMPETS. 



The limpets have but one valve. It is sometimes saucer 



