PSAMMOBIA. 397 



tured and forms the upper side of an obtuse angle: beaks 

 small, pointed, some what calyciform, almost contiguous, slightly 

 turned towards the posterior side : ligament rather short, pro- 

 minent, keeping the valves asunder in that part : hinge-line 

 obtusely angular : hinge-plate thick, broader on the posterior 

 side, abruptly truncate at the outer end of the ligament : teeth, 

 in the right valve two triangular, somewhat diverging, and 

 nearly equal-sized cardinals ; in the left valve a central car- 

 dinal of the same size and a minute laminar one set obliquely 

 or at a right angle to the hinge-plate ; the three largest teeth 

 are bifid : inside- thickened, highly polished, and partially iri- 

 descent, usually stained with purple or lilac : pallial scar dis- 

 tinctly marked, sinuated as in the two last species : muscular 

 scars irregularly triangular. L. 1. B. 1*8. 



Var. elongata. Shell broader or more produced at each end. 



HABITAT : Rather common on all the British coasts, 

 in sandy and nullipore ground, at depths of from 4 to 

 90 fathoms. The variety is from Ullapool. Fossil at 

 Preston (J. Smith); Belfast (Grainger); Coralline Crag 

 (S. Wood). The exotic distribution of this species, both 

 north and south, is extensive, and embraces Iceland 

 (Leach), Faroe Isles (Chemnitz), Scandinavia (Loven 

 and others), north of France (De Gerville and Mace), 

 coasts of Spain and Portugal and the Canaries (M f An- 

 drew), both sides of the Mediterranean (Scacchi, Wein- 

 kauff, and others), and ^Egean (Forbes), the range of 

 depth being between 3 and 40 fathoms in the former 

 case, and between 8 and 40 fathoms in the latter. Broc- 

 chi and Philippi have included it in their lists of tertiary 

 shells from Italy. 



Couch mentions having taken a specimen from the 

 stomach of a Picked Dog-fish, one of a predaceous tribe 

 that might have been supposed to disdain such " small 

 deer." The shells are always to a certain extent twisted, 

 and sometimes so much so as to be distorted. The fry 

 are triangularly oval. 



