LUCINA. 59 



rounded below, and obscui-ely subangulated above. The um- 

 bones are but moderately prominent, and incline forwards ; 

 the beaks are small and inflected ; in front of them is a 

 very short, not deeply impressed, lunule. The cartilage, 

 which is large and of a darker colour, occasionally of a 

 reddish-orange, is very obliquely seated in a groove of the 

 hinder hinge margin ; which latter is rather broad, and 

 gradually sinks inw^ards as it nears the posterior extremity. 

 There are no distinct lateral teeth, though sometimes a 

 rudimentary front denticle is found in the right valve, 

 which is furnished with a single primary tooth ; in the left 

 valve the cardinal teeth are two in number, but remark- 

 ably small in size. The muscular scars are very large ; the 

 front one, which is peculiarly narrow and elongated, runs 

 nearly parallel to the front of the palleal impression. 



The measured diameter of rather a large example was 

 exactly three-quarters of an inch. There is a dwarf ven- 

 tricose variety, taken chiefly at Guernsey (S. H.), of only 

 half an inch in length, and rather less in breadth, where- 

 in the hinder dorsal edge does not slope at all, the upper 

 posterior corner is subrectangular, the anterior indentation 

 and shallow groove are almost entirely obsolete, and the 

 surface, when highly magnified, appears radiated with 

 extremely delicate lineoles. 



The animal of this species was first examined by Poli, 

 who, recognising its remarkable peculiarities, constituted for 

 it his genus Loripes. He described and figured it as having 

 but one fistulose and wrinkled siphon ; a cylindrical, sub- 

 ulate, and very long foot, resembling a strap, and club- 

 shaped at the extremity ; the mantle, open in front, fur- 

 nished with two orifices, its margin crenulated ; no labial 

 palps ; the adductor muscles large and strong ; the general 

 colour white, ovaries milky, liver greenish. 



