162 GASTKOCH^ENID^E. 



valve is usually more convex than the left, which in most 

 specimens locks into it, like that of the Pandora obtusa and 

 Corbula nucleus. This species, though less smooth and regular 

 than our Sphaenia Binghami, is nevertheless extremely similar 

 both as to shell and animal, and has, in consequence, been 

 often confounded with it; it is, however, distinct, and the 

 dentition always preserves a constant different character. 



VENERIRUPIS, Lamarck. 

 V. IRUS, Linnaeus. 



V. irus, Brit. Moll. i. p. 156, pi. 7- f. 1, 2, 3 ; (animal) pi. G. f. 2. 

 Donaae irus, Auctorum. 



Conchologists, by the character of the teeth of the only 

 species of this genus, would place it amongst the Veneridte, 

 but malacology informs us, that it is as decided a member of 

 the Gastroch&nidce as Saxicava. We have examined a fresh, 

 though not a live animal, taken alive on the southern coasts ; 

 the closed mantle, foot, and siphons are similar to the Saxi- 

 cava. Dead shells are often procured in the red sandstone at 

 Exmouth, but it has not occurred there in a living state ; it is 

 only found in deposits that have been partially deserted by the 

 sea ; we have little doubt, that if the rocks which are never 

 uncovered at the lowest tides could be examined, it would 

 be found alive. We have here a practical illustration of the 

 superior attributes of malacological determinations. 



PANOP^EA, Menard de la Groye. 



P. NORVEGICA, Spengler. 



P. norvegica, Brit. Moll. i. p. 174, pi. 11, and iv. p. 249. 

 My a norvegica, Auctorum. 



Animal oblong, thick, pretty much the shape of the shell, 

 which gapes basally at the anterior end, and is obliquely 

 truncate posteriorly, with a very large gape. Mantle thick, 

 closed, except the pedal and siphonal apertures, pale drab, 

 but covered with a black skin. The orifice for the issue of 



