400 TELLININiE. 



Genus MACOMA, Leach. 



Animal with a single branchial lamella on each side. 



Shell oval, convex or sub-ventricose. Hinge with the 

 cardinal teeth small; no lateral teeth; ligament external. 

 Tallial impression with a deep, wide sinus. 



Ex. M. tenuis, Da Costa, pi. 104, fig. 2. Shell, M. 

 solidula, Pultney, fig. 2, a, 2, b. 



" The branchial apparatus," says Clark, " is curious, and a 

 departure from the Tellina type; it consists of a single, 

 rather elongated branchial plate on each side, situated to- 

 wards the posterior half of the animal; it is fixed to the 

 dorsal range by its base running obliquely, indeed almost 

 vertically, from the dorsal to the ventral range, becoming 

 joined to its fellow under the posterior and smaller part of 

 the body by a permanent membrane." The palpi are very 

 large and triangular. 



Species of Macoma. 



sequalis, Desk. contabulata, Desk. 



ala, Hanley. crassula, Desh. 



ancilla, Hanley. Cumana, Costa. 



Aurora, Hanley. dilatata, Desh. 



Balthica, Linn. discolor, Phil. 



Birmauica, Phil. Dombei, Hanley. 



Bruguieri, Hanley. edentula, Brod. and Soiv. 



calcarea, Chem. elougata, Hanley. 



callosa, Desh. Fabricii, Hanley. 



Candida, Lam. formosa, Hanley. 



Chinensis, Hanley. fragilis, Fabr. 



compressa, Desh. frigida, Hanley. 



concinna, C. B. Adams. fusca, Say. 



constricta, Brug. Galathsea, Lam. 



