CONCHIFERA. 749 



valve, single tooth in left ; a triangular pit receiving internal liga- 

 ment. External ligament small. Animal with tracheae long, 

 slender, separate, very unequal. 



Sp. Trigonella plana LOVEN, Macira piperata GMEL., Lutraria compressa 

 LAM., BLAINV. Malac. PL 77, fig. 2; EASTER Natuurk. Uitsp. n. Tab. 

 vin. figs. 57. This species keeps itself deep in the sand on sea-coasts, 

 and also occurs fossil in the Crag-formation. 



Cumingia SOWERBY. 



Sp. Cumingia tellino'ides DESH. Conchyliol. PL 8 bis, figs. 9 n; all the 

 species exotic. 



Mesodesma DESH. 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 tracheae separate (Peroncea POLI). 



Sp. Mesodesma Quoyi DESH., Conchyl. PL 10, figs. 13, 14; Mesodesma 

 cornea DESH., Amphidesma donacilla LAM., POLI Testae. utr.*Sicil. Tab. 

 xix. figs. 8 n (Mactra cornea, habitus almost of Donax). 



G-nathodon GRAY, Rangia DESMOULINS. 



Sp. Gnathodon cuneatus GRAY, DESH. Conchyl. PL 10, figs. 9 12. Comp. 

 RANG, Nouv. Ann. du Mus. in. 1834, pp. 217 230, PL 12. This species 

 lives in the brackish water of the great lake PontcJtartrain in Louisiana. 



Anatinella Sow. 



Sp. Anatinella Siblaldii Sow., Mya CHEMN. Conchyl. Tab. 3, figs. 17, 18, 

 DESH. 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 POLI) with tracheae coalesced, foot 

 compressed. 



Comp. L. SPENGLER Beskrivelse over det Slaegt Mactra. Skrivter of 

 naturhist. Selskdbet, v. 2. Kjobenhavn, 1802, pp. 92 128. 



Mactra LAM. Shell trigonal, tumid at the points. Two lateral 

 compressed teeth in left valve, received between two lamellae of 

 right valve. 



Sp. Mactra stultorum L., POLI Test. ulr. Sic. i. Tab. 18, figs. 10 12, BLAINV. 

 Malac. PL 73, fig. 5, Cuv. R. Ani., ed. ill., Moll. PL 107, figs. 2, -2 a; 

 brownish grey, with light radiating striae, purplish within ; very common m 



