56 INVERTEBRATA OF MASSACHUSETTS. 



GENUS CUMiNGIA BROD. and SOWERBY. 



Shell ovate, inequilateral, equivalve ; a shallow spoon-shaped car- 

 dinal tooth, and a single small tooth by its side in each valve, and a 

 strong lateral tooth on both sides in one valve only ; palleal impres- 

 sion with a large sinus. 



CUMI'NGIA TELLINO'IDES. 



Shell ovate-triangular, thin, white, nearly equilateral, pointed 

 and warped behind ; surface with sharp, elevated lines of growth. 



FIGURE 34. 

 State Coll., No. 225. Soc. Cab., No. 1744. 



Mactra tellinoides, CONRAD ; Journ. Jlcad. JYat . Sc., vi. 258, pi. 9, f. 2, 3. Amtr. 



Mar. Conc/t., 60, pi. 14, f. 2. 

 Cumingia tellinoides, CONRAD ; Journ. Jlcad. Nat. Sc. } vii. 234. 



Shell transversely triangular-ovate, thin, fragile, bluish-white ; 

 nearly equilateral, anteriorly broad, tumid, and regularly rounded ; 

 posteriorly compressed, warped, epding in a rounded point, the 

 margin declining more rapidly than in front ; beaks raised, not in- 

 clining to either end. Stages of growth marked by sharp, raised 

 ridges, which are crossed by microscopic, radiating lines ; in 

 front of the beaks is a small, well-defined areola. Within, glossy- 

 white ; pit for the cartilage shallow, directed slightly backwards ; 

 in front of it, in each valve, is a linear tooth forming part of its 

 wall, and at its side a fossa for receiving the corresponding tooth ; 

 lateral teeth distinct in the right valve, J)ut wanting in the left, the 

 anterior one longest. Muscular impressions faint, palleal impres- 

 sion far within the shell, with a broad, deep indentation opposite 

 the base. Length f inch, height -/o inch, width inch. 



Found abundantly in the region of New Bedford and Martha's 

 Vineyard, and probably may be found everywhere south of Cape 

 Cod. 



Its warped, slightly folded end gives it the aspect of a TELLI'NA. 

 Its shape and surface is similar to those of Corbula contrdcta of the 

 same size. The raised lines are, however, thin, elevated, sharp in 

 this, while in C. contrdcta they are thick and rounded, and the shell is 

 so much more compressed as to preclude mistake. 



A species of this genus is found in the West Indies, perhaps the 



