112 



PECTUNCULUS brevirostris. 



TAB. CCCCLXXIl.— ^^. 1. 



Spec. Char. Transversely obovate, rather ot)- 

 lique, and inequilateral, convex, obscurely 

 costated, concentrically striated; hinge 

 line rather straight ; beaks short, not ob- 

 lique ; hinge teeth few. 



X MERE is a slight elevation of the surface along thef 

 anterior side from the beak to the edge, where it pro- 

 duoes a gentle projection, and a little below this is the 

 greatest length of the shell ; the costae are convex, but 

 so little elevated as to be hardly discoverable in some 

 parts: some specimens have elevated lines between 

 them, but possibly they are the effect of wear ; the teeth 

 of the hinge are few, and very oblique ; below the area 

 of the ligament, it is more inequilateral, less convex, and 

 not so square as P. pulvinatus of Lamarck. 



An abundant and well known shell in the Bognor 

 Rocks ; I have never observed any variation of conse-^ 

 quence in its form; it wants the heartshaped space 

 described by Brocchi in his Area insubrica, and has 

 shorter beaks. 



PECTUNCULUS sublaevis. 



TAB. CCCCLXXIL— /o^, 4. 



Spec. Char. Transversely obovate, equilate- 

 ral, rather gibbose, with many slightly 

 elevated ribs ; beaks short, nearly close ; 

 sides smooth. 



Both the sides of this shell are nearly destitute of ribs; 

 there is a depressed space upon the anterior, which 

 bounds a convex surface near that extremity of the hinge; 

 the large hinge teeth occupy a regular arch below the 

 area for the ligament, which area is small; the teeth 

 upon the edge of the shell, are small and regular. 



Found in loose yellow sand at Blackdown, where the 

 substance of the shell is replaced by Silex. 



