GINGLYMACONCHA. MYAD. 273 
. STIRPS III. 
Shell gaping at each extremity: the process which bears 
the internal opening ligament vertical in both valves: the 
umbones are situated before the middle of the shell. 
The genera composing this Stirps were formerly arranged 
with the Mactre. 
Genus 21. LuTraria. 
Lutraria, Lamarck, Cuvier. 
Shells oblong, ovate, compressed ; umbones before the mid- 
dle of the back ; epidermis thin and smooth ; hinge in each 
valve, behind the ligament, with a small lamelliform tooth ; 
left valve with a triangular tooth before the opening ligament ; 
respiratory tubes very large ; foot large, acuminated on each 
side towards its apex, abruptly compressed, the apex itself 
rounded ; the aperture for its exit, elongate; branchie with 
their posterior extremities free. 
LUTRARIA ELLIPTICA. 
Shell smoothish, faintly striated concentrically ; epidermis 
greenish. Length five inches ; height two inches and a half. 
Mactra lutraria, Linn. Syst. Nat. xi. i. 1126; Penn. Brit. 
Zool. iv. 92. t. li. f.44 ; Mont. Test. Brit.1.110; M. § R. 
Trans. Linn. Soc. viii. 73; Dill. Dese. Cat. 146; Turt. 
Conch. Dict. 84. 
Lutraria elliptica, Lam. Syst. des Anim. sans Vert. 120; Hist. 
Nat. des Anim. sans Vert. v. 468. 
Lutraria vulgaris, Flem. Edinb. Encycl. vii. 92. 
This species is common along the coasts of Cornwall ; it 
occurs likewise in the Kingsbridge Estuary, at Dawlish, 
Paington, Torbay, and on the shore of Caermarthen, near 
Laugharn. 
NO 
