16 LEPIDOPLEURUS. 



In sculpture this species is strikingly different from the other 

 Leptochitons, and in fact from all other Chitons. The lateral areas 

 and front valve are strongly terraced, the latter being compared by 

 Carpenter to a circular flight of rounded steps. 



The Atlantic specimens are always larger than those from the 

 Mediterranean, the measurements^?^ given above being taken from 

 an Ocean example, the second measurements from an Italian speci- 

 men. 



It is the type of Risso's genus Lepidopleurus. 



Section Deshayesiella Carpenter, 1878. 



Desliayesiella CARPENTER mss., p. 10. BALL, Proc. IT. S. Nat. 

 Mus., 1878, p. 314; I.e. 1882, p. 286. HADDON, 'Challenger' 

 Polyplacophora, p. 9. 



Shell elongated ; valves curved, somewhat beaked ; umbo flat- 

 tened ; no insertion plates ; sutural plates triangular ; girdle spicu- 

 lose. 



Differs from Leptochiton not only in its hairy girdle but also in 

 its flattened umbo and its valves, which are somewhat thrown for- 

 ward, forming a decided transition toward some of the palaeozoic 

 forms. ( Qpr.) 



L. CURVATUS Carpenter, n. sp. PI. 4, figs. 78, 79, 80, 81. 



Shell rather elongated, whitish-ashen, planate; dorsal ridge 

 rounded ; umbo central, flat ; valves with pointed apices, all curved ; 

 the interior of the posterior part of each valve much scooped out. 

 Jugal area broadly V-shaped, quasi reticulated, the lines of pus- 

 tules parallel in the middle, diverging at the sides, interstices punc- 

 tate. Central areas with longitudinal distant, beaded lines, 8 to 10 

 on each side, tending toward the jugum forward, interstices decus- 

 sated. Lateral areas somewhat swollen, expanded, but scarcely 

 defined by a line from the central areas ; coarsely, irregularly gran- 

 ose, and concentrically waved. 



Inside: insertion plates absent, the position of them flat; sinus 

 broad, following the curvature of the valve. 



Girdle delicate, clothed with small scattered spines, occasionally 

 larger, and chaffy scales. ( Qor.) 



Length 14, breadth 6 mill.; div. 120. 



Okosiri, Japan (A. Adams). 



