268 TESTACEOUS MOLLUSC A. 



margin of the anterior hiatus formed by an internal rib ; auricles 

 small, anterior acute, posterior obtuse ; hinge area narrow. 1,50. . 

 0,80. Tahiti and Philippines. 



L. Arcuata. Sow. Th. p. 86. t. 22./. 41, 2. Closely resembling 

 the last but more gaping, and having the ventral margin expanded 

 and slightly angular. 1^...-^ Panama, fyc. 



L. Aperta* Sow. Th. p. 87. t. 22./. 26, 7, 8, 9.— L. Tenera. 

 Turt.Zool.J.2.p.362.t. 13./. 2.— Phil. p. 77.— L. Bullata. 

 Payr. Corsic. p. 70. Thin, rather flat, obliquely oval or elongated, 

 smooth at the sides, minutely striated in the middle : posteriorly 

 slightly, anteriorly widely, gaping, the anterior hiatus margined by 

 a strong internal rib ; anterior auricles acute : hinge area small. 

 t 9 q. .f Britain. l 



L. Dentata Son: Th. p. 87. t. 22./. 30,1. Obliquely elongated, 

 thin, rather compressed, the posterior side slightly, the anterior ra- 

 ther more widely gaping ; a slight internal rib, forms the margin of 

 the anterior hiatus ; anterior auricles extremely sharp, with a 

 notch underneath them ; hinge area deep ; ribs eighteen, distant, 

 granulated, their terminations producing a dentated ventral margin. 

 JL , , I 



°L. 2 Cumingii Sow. Th. p. 87. t. 22, /. 24, 5. Thin, small, 

 obliquely elongated, rather inflated, nearly five-sided, almost closed 

 at the margins ; anteriorly very slightly gaping, ventral edge sub- 

 quadrate ; hinge short; auricles short and rather obtuse; anterior 

 margin obtusely angulated ; ribs twelve, central, nearly obsolete, 

 toothed at the margin. 0,40. . 0,25. Isle of Luzon, Philippines. 



PECTEN. 



Free, regular, inequivalve eared ; the dorsal edge transverse, straight; 

 beaks contiguous : hinge without teeth ; ligament internal, placed 

 in a triangular cavity. 



P. Maximus* Lam. I.— Sow. Th.f. 98 to 100.— Turt. B.p. 207 

 —Mont. p. 143.— E. t. 209. / 1.— Ostrea M. Lin. 1144.— D. 

 p. 247. — Knorr. 2. t. 14./. l.— W. t. 11./ 1. Suborbicular, 

 rather spread at the sides, rather depressed ; umbones smooth, 

 margins striated ; upper valve concave near the umbo, slightly 

 elevated near the middle ; auricles large, rectangular, striated : hinge 



1 Probably the Ostrea Hians of Gmelin, a species wholly derived 

 from the figure in Schroeter's Einlungen t. 9./. 4. (/). p. 270. — W. 

 t. 11./ 53. — L Linguatula var ? Lam.) is an aged specimen of 

 this species. 



