274 CONRAD'S DESCRIPTIONS OF NEW FOSSIL SHELLS OF THE U. S. 



AVICULA. 



A. ABRUPTA. PI. 24, fig. 5,6. — Suborbicular, convex; posterior margin nearly direct; extremity of hinge 

 on a line with the posterior margin. 



Locality. Nimrod Woodward's farm, N. J. 



This small species is well preserved, but very tliiti and fragile. I found two right 

 valves, one of them perfect. 



A. PETROSA. PI. 2t, fiir. 15. — Subquidrangular, very oblique, ventricose; anterior hinge extremity sharply 

 angulate(1; anterior margin obliquely subtruncated inferiorly; posterior extremity subangulated. 



Locality. Chesapeake and Delaware canal. 



A single cast of this species is in the collection of the Academy. On the apex are 

 two tubercles, which must represent corresponding pits in the interior of the shell. 



SOLEMYA. 



S. PLANULATA. PI. 24, fig. 11. — Elliptical, compressed, sidcs flattened ; end margins rounded; hinge and 

 basal margins nearly par llel. 



Localities. Monmouth county, N. J. ; Alabama. 



Casts of this species are not uncommon in the Cretaceous limestone of Alabama. 

 They exhibit a flat groove, which margins the posterior side of the anterior cicatrix; 

 this groove represents the interior rib, and rapidly widens from its inferior acute 

 extremity towards the apex. 



CRASSATELLA. 



C. SUBPLANA. PI. 24, fig. 9. — SuLtriangular, coinpre.s.sed or piano- convex ; anterior margin obtusely 

 rounded ; posterior extremity subtruncated ; posterior basal margin straight or slightly contracted ; dirk 

 marked with numerous prominent acute concentric ridges and fine concentric lines. 



Locality. Arneylown, N. J. 

 Allied to C. rcgularis, D'Orbigny. 



SPONDYLUS. 



S. CAPAX. PI. 24, fig. 8. — Ova'o-triingular, profoundly ventricose; summit elevated; ribbed; larger rib.s 

 about seven in number, not eLvated, remo'e and armed with irregular spines, arched or foliated, a few 

 of them rather elongated, curved and pointing downwards ; intermediate ribs rounded, unequal, not very 

 proaiinent and rough with numerous arched .scales; subniargiual areas profoundly impressed orexcavated; 

 inner margin thickened and profoundly creuat2. 



- Locality. Nimrod Woodward's farm, N. J. 



I have found fragments of this beautiful fossil, whenever I have visited the locality 

 above named, for many years past, and more than fifteen years since obtained a 

 whole specimen, which was presented to my friend, Dr. Wm. Fleming, of Manches- 

 ter, England. Yet it does not appear to have been described, and may have been 

 regarded as a variety of Morton's Plagiostoma diimosum, an Eocene species. 



