30 CONCHOLOGY. 



S. vagina. The Razor Sheath. PL 31, fig. 5. 

 Valves equal, truncated at both ends ; straight or slightly 

 curved ; summit terminal. 



S. cultellus. The kidney-shaped Solen. 



Species a little curved lengthwise ; summit not terminal. 



/S. rostratus. The violet-beaked Solen. 



Species with longer and narrower valves, flatter at the ex- 

 tremities ; callosity at the hinge very visible ; cardinal teeth 

 or hinge nearer the middle than the anterior side. 



S. ensis. The Sabre Solen. 



Species linear, sabre-shaped ; a single compressed tooth 

 in each valve ; olive brown at the base, and of a purple hue 

 near the apex. 



S. siliqua. The podlike Solen. 



Species linear, straight; two teeth in one valve and one 

 in the other ; covered with a glossy brown epidermis ; stri- 

 ated transversely. 



S. antiquatus. The Antiquated Solen. 



Species thin, white, and almost transparent ; striated con- 

 centrically ; ends rounded ; hinge near the centre ; a tooth 

 in one valve locking into two in the other; the teeth erect 

 and projecting beyond the margin ; covered with a dark-col- 

 oured epidermis. 



2. Panopsea. One species. 



Distinguished from the Mya by the prominency of the 

 apex and the situation of the ligament. 



Shell regular, elongated oval, gaping at the two extremi- 

 ties, equivalve, inequilateral ; summit but little marked, and 

 anterodorsal ; hinge very complete, similar, formed by a 

 conical primary tooth before a short, compressed, ascending 

 callosity ; ligament exterior, attached to the callosity ; two 

 muscular impressions. 



