BIVALVIA. 221 



more or less uncoated. Unlike the preceding species, this is free from radiating striae, 

 and the margin is in consequence quite smooth. The form of this is also different, 

 and may be readily distinguished. The palleal sinus is large and deep, extending 

 beyond the hinge area, and in some old shells the interior is considerably thickened. 



Poli has given a good representation of the shell of this species ; but in depicting 

 the animal he has made the siphons to protrude on the longer, and the foot at the 

 shorter or posterior side. 



PSAMMOBIA,* Lam. 1818. 



Lux. Chemn. 1782. 

 GARI. Schum. 1817. 

 PSAMMOT.EA. Lumk. 1818. 

 PSAMMOTEA. Schweig. 



PERON^A et PERON^EODERMA (sp.) Poli. 



AZOR. Leach, MS., 1819 

 _ 



GOBR^EUS. Id. 



PSAMMOCOLA. Blainv. 1824. 



. 1 

 ^ 



. Gray. 



Generic Character. Shell equivalve, subequilateral, transversely oblong, more or 

 less compressed, slightly gaping at each extremity; exterior generally covered with 

 transverse or concentric striae, and occasionally ornamented with radiating lines or 

 ridges. Hinge composed of two teeth in one valve, and one in the other, and without 

 lateral teeth. Sinus in the impression of the mantle large and deep. Ligament 

 external, fulcrum prominent. 



The animal has the mantle open the entire length, and bordered by a fringe of 

 fine simple filaments ; siphons long and slender, marked with longitudinal lines, and 

 ornamented with minute cirri ; a large and tongue-shaped foot, somewhat pointed. 



There is no very essential distinction between this genus and Tellina, the 

 greatest difference appearing to be a somewhat more oblong form of outline, and 

 a less distinct inflexion on the posterior side of the shell, with a rather more 

 prominent fulcrum for the ligament in Psammobia. In the recent state the 

 species are, like the Tellens, inhabitants of various climes, and generally live buried in 

 sand or gravelly mud, and they have a vertical range from low- water mark to 100 

 fathoms. 



The name of this genus, being in fact only third in point of date, will have to be 

 changed. 



1. PSAMMOBIA FERROENSIS, Chemn. Tab. XXII. fig. 3, a, b. 



Petwer. Gazophyl., t. 94, fig. 9, 1764. 



TELLTNA FERROENSIS. Chemn. Conch. Cab., vi, p. 99, t. 10, fig. 91, 1782. 

 FEROENSIS. Broc. Conch. Subap., p. 512, No. 6, 1814. 



* Etym. ^>afjtfjtos } sand, and ftivu, to live. 



