202 



C. (?) PARVULA, (n. sp.) Shell small, thick, subovate, triangular, 

 very gibbous ; anterior margin strongly rounded ; posterior end 

 obliquely truncated from beak to postero-inferior extremity, and form- 

 ing with the pallial margin an angle of about 50° ; umbonial region 

 very gibbous ; posterior area rather broad-ovate, forming with the 

 side of the valve, nearly a right angle, and marked with an obtusely 

 rounded ridge, which extends from behind the beak to the postero- 

 inferior extremity; beaks elevated, incurved, situated between the 

 middle and anterior extremity ; surface marked with irregular, con- 

 centric folds and fine stria3 of growth. 



I have not been able to see the hinge of this species, and it is, 

 therefore, placed in the genus Crassatella^ with a mark of doubt. 



Length, 0.40 inch ; height, 0.30 ; thickness, 0.28. 



Lower Cretaceous, Red River, Fannin County. Collected by Dr. 

 G. G. Shumard. 



Genus Cucull^a, Lamarck. 



C. MiLLESTRiATA, (n. sp.) Shell somcwhat trapeziform, gibbous, 

 rather thin, a little longer than wide, narrow before and broad pos- 

 teriorly ; cardinal extremities rounded, margin straight ; anterior 

 margin neatly rounded ; posterior margin obliquely truncated, and 

 strongly rounded at inferior extremity ; pallial margin gently convex ; 

 beaks moderately elevated, rather sharp at tip and located a little 

 before the middle ; surface marked with numerous, very fine concen- 

 tric strige of growth and radiating lines ; hinge with from thirteen to 

 fourteen strong teeth, arranged In an arcuate series ; hgamentary 

 area, very narrow, lanceolate ; posterior muscular impression bounded 

 internally by a thin elevated septum. 



Length, 0.88 inch ; width, 0.70 ; thickness, 0.52. 



Lower Cretaceous, Red River, Lamar County. 



Dr. G. G. Shumard and A. Roessler collectors. 



Genus Nucula, Lamarck. 



N. BELLASTRiATA, (n. sp.) Shell small, subovate, or more or less 

 triangular, transverse ; umbonial region gibbous, sloping to posterior 

 end and base ; beaks near the anterior extremity, more or less ele- 

 vated, pointed (in cast) ; buccal side very short, rounded, obtusely 

 subangulated ; posterior side cuneate ; base gently arched ; cardinal 

 border very sHghtly convex posteriorly, anterior muscular imjiression 

 broad, subovate ; hinge with from eighteen to twenty slender, closely- 

 set teeth behind, and from eight to ten before the beaks. Surface 

 elegantly ornamented with fine concentric lines of growth and numer- 

 ous fine crowded strite, which commence at the beaks and radiate to 

 the margins. 



Length, 0.49 inch ; width, 0.30 ; thickness, 0.24. 



