LEPIDOPLEURUS. 



' Lightning' dredgings, says that it differs from the white variety of 

 cinereus \==asellus~] in its comparatively greater length and more 

 raised or arched form, in the less distinct or regular catenation of 

 the granules which cover the surface, and in the prominence of the 

 lateral areas. 



L. ALVEOLUS Sars. PI. 2, figs. 23-31. 



Shell quite convex, back equally arched, without trace of a keel 

 or defined lateral areas ; valves rather elongate, the posterior larger 

 than the anterior valve, half-round, truncated by a straight line in 

 front; median valves subequal, their posterior margins straight, 

 anterior margins lightly emarginate in the middle. Entire surface 

 sculptured with minute ovate tubercles, regularly disposed. (Sars.} 



Length 16 mill. 



North Atlantic at Bergen, Lofoten, Finmark, 150-300 fms. ; Bay 

 of Biscay, 120-664 fms. ; Gulf of St. Lawrence between Cape Rosier 

 and the S. W. point of Anticosti Id., 220 fms. ; St. George's Bank, 

 Gulf of Maine, 150 fms. 



Chiton alveolus (SARS ms.} LOVEN, Ind. Moll. Lit. Scand. p. 27, 

 159, 1846. JEFFREYS, P. Z. S. 1882, p. QQS.Lepidopleurus alve- 

 olus G. O. SARS, Moll. Reg. Arct. Norv. p. 110, t. 7, f. 3 ; t. i, p. 7, 

 lS7S.Leptochiton alveolus DALL, Proc. U. S. Nat. Mus. 1878, p. 

 317. HADDON, Challenger Rep. vol. xv, p. 12. 



L. PERGRANATUS Dall. Unfigured. 



Shell elongated, moderately elevated, regularly arcuate, without 

 jugum. Pale waxen, sometimes white. Valves wide, without 

 apices. Front and back valves more or less concave; posterior 

 valve without elevated apex. Sculpture as in L. cancellatus, but 

 the granules larger, lateral areas less defined. Sutural plates elon- 

 gated. Girdle wide, densely beset with delicate scales. (Dall.) 



Length 12, breadth 6 mill. 



Near Dominica, West Indies, in 138 fms. 



Leptochiton pergranatus DALL, 'Blake' Rep. p. 414, 1889. 



This fine species is nearest the Atlantic L. cancellatus Sowerby, 

 and the Japanese L. fuliginatus Ad. & Reeve. It differs from both 

 in its concave or excavated, instead of convex, terminal valves, in 

 the absence or obsolete condition of the posterior mucro, in its 

 much larger and more regular granules, and in the subdepressed 

 appearance also of the part of the median valves near the girdle 

 on each side. It is larger than cancellatus and smaller than full- 



