BIVALVIA. 



273 



2. NE^RA CUSPIDATA, Olivi. Tab. XXX, fi. 6. 



o 



TELLINA CUSPIBATA. Oliv. Zool. Adriat., p. 101, pi. 4, fig. 3, A c, 1792. 



Sroc. Conch. Foss. Subap., p. 515. 

 ANATINA BREVIROSTBIS. Brown. Ed. Journ. Nat. and Geo. Sci., vol. i, p. 11, pi. 1, 



figs. 14, 1829. 



THRACIA BREVIROSTRA. Brown. 111. Conch. Gr. Br., pi. 44, figs. 11 14, 1845. 

 NE^RA BREVIROSTRIS. Loven. Ind. Moll. Scand., p. 48, 1846. 



CUSPIDATA. Forb. and Hani. Hist, of Brit. Moll., p. 195, pi. 7, figs. 4 6; and 



pi. G (animal), figs. 47, 1848. 

 Forbes. JSgean Inv., p. 185. 



CORBULA CUSPIDATA. Phil. En. Moll. Sic., vol. i, p. 17, t. 1, fig. 19 ; and vol. ii, p. 12. 

 SUBROSTRATA. S. Wood. Catalogue, 1840. 



A fragment only of a shell, which I consider to belong to this species, was found 

 by myself in the Coralline Crag at Sutton, but it is insufficient for correct descrip- 

 tion : the peculiar form of the siphonal side (the portion I possess) is so characteristic 

 that it is introduced here without much hesitation. It appears to have belonged to 

 the British or short beaked variety. 



CORBULA.* Bruyviere, 1792. 



MYA (sp.) Linn. Mont. 

 CARDIUM (sp.) Walker and Boys. 

 TELLINA (sp.) Olivi. 

 AI.OIDES, Megerle, 1811. 



LENTIDIUM, Cristof. and Jans. 1832. 

 POTOMOMYA, J. Sowerby, 1835. 

 AZARA, D'Orb. 1839. 

 CORBULOMYA, Nyst, 1843. 



Generic Character. Shell suborbicular or ovate, inequivalve, inequilateral, tumid, 

 closed ; beaks prominent, recurved surface smooth or striated ; in the recent state 

 covered with an epidermis. Hinge composed of one thick, conical tooth in each valve. 

 Ligament internal. Impression by the mantle with a small sinus. 



Animal short ; mantle open in front for the emission of a thick foot, of 

 considerable magnitude; siphonal tubes short and united to their orifices, which 

 are fimbriated : anal opening with a conspicuous tubular membrane. 



Animals constituting this genus are for the most part inhabitants of salt water, but 

 some are estuary species, and extend their range in the river to where the water is 

 quite fresh. A separation has been proposed, under the name Potomomya, for those 

 species which permanently inhabit fresh water, but the characters of shell and animal 

 differ in no other respect from those which are truly marine. In this genus, as well as 

 in that of Pandora, the two valves are very unequal in size, but this inequality is not 

 confined to the siphonal side of the shell, and the sinus of the mantle-mark does not 



*Etym. ? Corbula, a little basket. 



36 



