LEPIDOPLEURUS. 6 



genus in Gray's edition of Leach's Synopsis Moll. Gt. Brit., in 

 1852, need not be considered here as it has no bearing upon nomen- . 

 clature. In 1858, Messrs. H. and A. Adams, in the Genera of 

 Recent Mollusca, adopted Risso's name for a large list of species 

 composed mainly of Ischnochitom, but including also species of 

 Callochiton, Leptochiton , etc.. among them L. cajetanus Poli. Car- 

 penter in his later writings used Lepidopleurus tu cover that group 

 of Ischnochitons having the girdle clothed with large, smooth con- 

 vex scales, like those of the typical Chitons. Nothing can be said 

 in favor of this use of the name, for Carpenter expressly states that 

 the species cited by Risso are excluded from the group as rehabili- 

 tated ! It is, therefore, obvious that Lepidopleurus Cpr. is a totally 

 distinct group from Lepidopleurus Risso. No argument is needed 

 to show the imtenability of Carpenter's position. In 1889, Carus, 

 in his Prodromus Faunce Mediterranean, has used Lepidopleurus as a 

 subgenus under Chiton (which he places in the Ischnoidea !), and 

 has included in it species of Trachydermon and Ischnochilon, as 

 well as Leptochiton cajetanus. In 1878 G. O. Sars correctly 

 restricted Lepidopleurus to the genuine Leptochitons. 



L. CANCELLATUS Sowerby. PI. 3, figs. 54, 55, 56, 57, 58. 



Shell small, elongated, much elevated, regularly arched, not 

 angled. Orange-ashen or whitish. 



Anterior valve radiately, evenly, very finely, granose-lirate. 



Central areas of the intermediate valves having distinct longitu- 

 dinal, fine, close granulous lirse, the granules being sometimes 

 arranged in transverse lines also, giving a latticed appearance ; lat- 

 eral areas distinct, decidedly raised, convex, having radiating but 

 rather irregular rows of granules. 



Posterior valve with central elevated apex ; posterior slope con- 

 cave. 



Interior white, the sutural plates small, triangular; jugal sinus 

 very broad. 



Girdle narrow, densely beset with delicate, scarcely imbricating 

 or striated, scales (figs. 55, 57). 



Length 51, breadth 2 mill.; divergence 80. 



Northern Atlantic and Arctic Seas. Britain; Norwegian Coast 

 in 50-100 fms. ; Lofoten Is. 300 fms. ; Greenland; South to Gulf 

 of Lyons, Vigo, Spain (jund Dalmatia /). Northern Pacific. Alaska, 

 at Unalashka, Shumagins, Port Etches and Sitka Harbor, 6-100 fms. 



