408 rilOCEKDiyaS of TIUC XATIONAL museum. voi..xxi. 



shells occuvriiig in the same hand specimens in the limestone. The 

 surface of the shell is marked by tine concentric lines and stria* of 

 growth and very line, interrupted, radiating striie. Oasts of the 

 interior of the shell show stronger radiating striae than the outer sur- 

 I'ace, also in many specimens nnnsually large ])apilla' that fill the i»its 

 or pnncta; on the inner surface. - The number and strength of the 

 l)ai)illa! varies in different casts. 



The shell appears to have been rather tliin and formed of a thin 

 onter layer and one or more thin inner hiyers or lamelhe. 



Casts of the interior of the ventral valve show a well delined area, 

 divided midway by the cast of a strong pedicle groove. The area of 

 the (hysal valve is obscured by adhering fragments. 



Casts of the ventral valve show traces of the visceral cavity (r) and 

 the main vascnlar sinuses (r,v). Jn the dorsal valve a narrow, long 

 median siiins is clearly defined; also the casts of the central and ante- 

 rior lateral muscle scars. 



Observalions. — This neat little species resembles in some respects O. 

 (/y.) simllh. It differs in being more elongate, the interior being more 

 strongly punctate, and in the more anterior position of the central 

 muscle scars in the dorsal valve. Some of the Wisconsin shells referred 

 to (). (/>.) simUis show greater length in proportion to the width than 

 those from the lUack Hills, Tennessee, and Georgia. This, however, 

 appears to be confined to a few shells. 



Formation and localitij. — Tpper Cambrian, limestones, Connasanga 

 shale, li miles south of Home, Georgia. 



Type.—liio. Ii7323, U.S.N.M. 



OBOLUS (LINGULELLA) LINEOLATUS, new species. 



General form ,ovate, with the ventral valve subacuminate and the 

 dorsal valve ovate to broad ovate. The range of variation in the out- 

 line of the valves is quite strongly marked. Th^ convexity of the valves 

 is moderate, that of the dorsal valve being a little ny)re than that of 

 the ventral. 



The surface of the shell is marked by concentric lines and stria' of 

 growth, with very line, concentric stria" between them that are some- 

 times slightly undulating; on some specimens very faint radiating stria' 

 can be seen with a strong lens; when the outer layer is exfoliated the 

 inner layer is marked by fine radiating and concentric stria' in addition 

 to the stronger concentric striae; as far as can be determined from tlie 

 imperfect casts of the interior, the inner surface of the shell was nearly 

 smooth. The shell a]ipears to be formed of a very thin outer layer and 

 one or more thin inner layers or lamelhe; toward the frontal margins 

 the oblique lamella' increase in number, but do not give any consider- 

 able thickness to the shell. 



One of the largest of the ventral valves referred without doubt to 

 this species has a length of 7 mm. and a width of 5 mm. An associated 



