64 CONCHOLOGY. 



P. pennaceus. P. striatularis. 



P. rubens. P. nummarius. 



P. castaneus. P. pectinatus. 



P. pectiniformis. P. radians. 



P. vitreus. 



P. glycimeris. The delicious Pectunculus. 



Sub-orbicular, umbones produced; finely striated trans- 

 versely and longitudinally ; covered with epidermis, under 

 which it is marked with reddish chestnut spots or bands ; 

 inside white ; margins crenulated. 



P. pilosus. The hairy Pectunculus. 



Species convex, more or less smooth and hairy. 



P. pectiniformis. The Pecten-shaped Pectunculus. PI. 

 11, fig. 6. 



Species lenticular, more compressed, pectinated, and more 

 or less rough. 



4. Nucula. Six species. 

 Shell small, more or less thick, sub-triangular, equi- 

 valve, inequilateral ; summits contiguous and turned for- 

 ward ; hinge similar, formed by a numerous series of very- 

 pointed teeth, pectinated and disposed in a line interrupted 

 under the summit ; ligament internal, short, inserted in a 

 small oblique cavity in each valve ; two muscular impres- 

 sions ; valves more or less pearly within. 



Nucula lanceolata. Nucula Nicobarica. 



N. rostrata. N. obliqua. 



N. pella. N. margaritacea. 



N. rostrata. The beaked Nucula. 

 Species of which the margin is entire, 



N. margaritacea. The pearly Nucula. PI. 11, fig. 7. 



Species of which the margin is crenated ; numerous regu- 

 lar pectinated teeth ; obliquely ovate, trigonal ; striae minute 

 and almost obsolete ; covered with a greenish epidermis ; in- 

 side silvery, pearl-like. 



