36 axatinid^e. 



tudinal. Petiver called the present species Chama prcc- 

 tenuis, or the " small, white, thin Spoon-hinge" Some 

 authors have referred it to Schumacher's genus Peri- 

 ploma ; but his description and figure give a different 

 and more complicated hinge-structure. Leach carved 

 out of it two other genera, Bontia or Bontcea and Ga- 

 laxura. It is the Anatina truncata of Lamarck, and A. 

 oblonga of Philippi, the former having been identified 

 by Collard des Cherres, and the latter by Sars, with 

 typical specimens. Collard des Cherres enumerated it 

 in his list as Beriploma myalls, and Chiereghini as Tel- 

 Una frag Ms sima ; S.Wood described it as Cochlodesma 

 prcetenerum. 



2. T. papyra'cea*, Poli. 



Tellina papyracea, Poli, Test. Sic. i. p. 43, t. xv. f. 14, 18. Thraeia pha- 

 seolina, F. & H. i. p. 221, pi. xviii. f. 5, 6, and (animal) pi. H. f. 4. 



Eody varying in colour from clear white to pale brown, 

 covered with minute and numerous tubercles or papilla?, that 

 give the surface a frosted appearance : mantle protruded con- 

 siderably at each end ; edges plain : tubes separate, cylindrical, 

 but short and wide, capable of being much inflated and un- 

 equally distended, sometimes club-shaped at their extremities ; 

 the upper tube is marked with eight, and the lower with four 

 faint longitudinal lines or streaks, which terminate at the 

 orifices in the same relative number of short, thick, and blunt 

 cirri : gills forming two large suboval plates, each divided in 

 the middle by a deep and oblique furrow ; they are smooth 

 within and pectinated without : palps equal-sized, short, and 

 triangular : foot flat and expansile, bluish- white. 



Shell thinner than the last species, and more inequivalve, 

 more convex (though compressed towards the front and sides), 

 and more elongated transversely : sculpture similar, but more 

 delicate : epidermis less persistent, and having usually a rusty 

 tinge on the posterior side : margins not so much rounded on 

 the anterior side, decidedly and more abruptly and obliquely 



* Paper-like. 



