lOyo SIMPSONFil.LA 



Key to species of »Simpsoneli-a 



Shell rather thin, nacre purple or copper}-. 

 Subrhomboid. 



Short, subshining. purpurea. 



Somewhat elongated, silky. subcrassa. 



Wide behind, dark. tenuis. 



i\Iuch elongated. gracilis. 



Obovate. crepera. 



Shell siibsolid. nacre lurid, tinted purpli.sh. 



With feeble concentric sculpture, subshining, crassa. 



With strong, concentric sculpture, dull. insularis. 



Group of Simpsonclla purpurea. 



Shell not biangulate behind, rather smooth ; nacre coppery- 

 purple ; teeth very faint, compressed. 



Simp.sonet.i.a pt^rpurea (Valenciennes). 



Shell subelliptical or subrhomboid, .scarcely inflated, rather 

 thin, inequilateral ; beaks only moderately full and high, point- 

 ed and turned slightly forward, sculptured with zigzag bars ; 

 anterior end rounded ; base line nearly straight, often a little 

 full behind the middle ; dorsal outline lightly curved ; dorsal 

 slope obliquely subtruncate ; posterior ridge and the lower part 

 of the hinder end rounded ; surface with delicate, irregular 

 growth lines : epidemiis brownish-copper\\ darker and with 

 an indistinct, green ray or two on the dorsal slope ; teeth rudi- 

 mentary, there being delicate, vestigial, lamellar pseudocar- 

 dinals and laterals ; muscle scars shallow ; nacre coppery with 

 radial markings ; prismatic layer wide, lurid coppery. 



Length 57, height 32, diam. 19 mm. 



Length 50, height 31. diam. 18 mm. 



Length 66, height 38. diam. 25 mm. 



Length 54, height 28, diam. 20 mm. 



Philippines. 



