CONCHIFERA. 749 
valve, single tooth in left; a triangular pit receiving internal liga- 
ment. [External ligament small. Animal with trachee long, 
slender, separate, very unequal. 
Sp. Trigonella plana Lovén, Mactra piperata Guew., Lutraria compressa 
Lam., Buarnv. Malac. Pl. 77, fig. 2; Baster Natuurk. Uitsp. 11. Tab. 
vill. figs. s5—7. This species keeps itself deep in the sand on sea-coasts, 
and also occurs fossil in the Crag-formation. 
Cumingia SOWERBY. 
Sp. Cumingia tellinoides DusH. Conchyliol. Pl. 8 bis, figs. g—11; all the 
species exotic. 
Mesodesma Desu. Shell transverse with anterior side longer, 
thick, shut. Ligament only internal, received in a narrow, deep 
pit. Hinge with one or two teeth under the point, and two 
lateral. Animal with two trachez separate (Peronea Pott). 
Sp. Mesodesma Quoyi DusH., Conchyl. Pl. 10, figs. 13, 14;—Mesodesma 
cornea DisH., Amphidesma donacilla Lam., Pout Testac. utr. Sicil. Tab. 
XIX. figs. 8—11 (Mactra cornea, habitus almost of Donax). 
Gnathodon GRAY, Rangia DESMOULINS. 
Sp. Gnathodon cuneatus GRAY, DEsH. Conchyl. Pl. ro, figs. g—12. Comp. 
Rane, Now. Ann. du Mus. 111. 1834, pp. 217—230, Pl. 12. This species 
lives in the brackish water of the great lake Pontchartrain in Louisiana. 
Anatinella Sow. 
Sp. Anatinella Sibbaldii Sow., Mya Curmn. Conchyl. Tab. 3, figs. 17, 18, 
DersH. Conchyl. Pl. 8 bis, figs. 4, 5. 
Mactra L. Shell transverse, inequilateral, subhiant at both 
ends. An excavated process under the points in hinge, receiving 
the internal ligament; cardinal tooth bifid or forked in front of pit 
for ligament. Animal (Callista Pot) with trachez coalesced, foot 
compressed. 
Comp. L. Spmnaier Beskrivelse over det Slaegt Mactra. Skrivter af 
naturhist. Selskabet, V. 2. Kjébenhavn, 1802, pp. 92—128. 
Mactra Lam. Shell trigonal, tumid at the points. Two lateral 
compressed teeth in left valve, received between two lamellx of 
right valve. 
Sp. Mactra stultorum L., Pout Test. utr, Sic. 1. Tab. 18, figs. 1o—12, BLAINV. 
Malac. Pl. 73, fig. 5, Cuv. R. Ani., éd. ill., Moll. Pl. 107, figs. 2, 24; 
brownish grey, with light radiating strie, purplish within ; very common in 
