SOLECURTUS. 259 



SOLECURTUS, Blainville. 



Shell transversely oblong, compressed, eqiil valve, sub- 

 equilateral, rounded and gaping at both extremities. Sur- 

 face more or less invested with an epidermis, sometimes 

 nearly smooth, sometimes ornamented with oblique grooves. 

 Hinge composed of two fine divergent primary teeth in each 

 valve. Ligament external. Inside of valves with two 

 strong muscular impressions, the anterior largest and lobed; 

 the pallial impression deeply sinuated. 



Animal very large and thick in proportion to the shell, 

 oblong ; mantle closed in front, widely open anteally for 

 the passage of a large linguiform foot, and posteriorly for 

 the siphons, which are deeply separated at their extremities, 

 united and forming a thick mass at their bases. Labial 

 palpi triangular, narrow, lamellated on their inner sides. 

 A large portion of the branchiae are lodged in the branchial 

 siphon. 



This very natural genus, which from habit many authors 

 have persisted in retaining as a portion of Solen., presents 

 affinities, both of shell and animal, with Lutraria on the one 

 hand, and Psammohia on the other. Solemya is perhaps 

 its nearest ally. It dates from the cretaceous, perhaps 

 from the oolitic period, and shells allied to it occur in still 

 older strata. Very near allies of existing forms are found 

 in the oldest of the tertiaries. 



S. coARCTATus, Gmeliu. 

 Surface striated only by concentric lines of growth. 



Plate XV. fig. 3, and (animal) Plate I. fig. 5. 



Solcn cuUellus, Pennant (not Linn.) Brit. Zool. ed. 4, vol. iv. p. 85, pi. 46, 



f. 25. 

 Ckama Solen, Da Costa, Brit. Conch, p. 238. 



