74 CHjETOPLEURA-ISCHNOCHITON. 



C. ASPERIOR Carpenter. PL 15, figs. 38, 39, 40, 41. 



Shell small, acutely keeled, the side-slopes straight. Buff-white, 

 marked with purple-black at each side of the dorsal ridge, and at 

 the outer extremity of each valve. Girdle tessellated light and 

 dark. 



The median valves are squared, minutely beaked ; lateral areas 

 slightly raised, and sculptured with about three radial rows of sparsely 

 placed pustules, subject to considerable irregularity. Central areas 

 having 7-9 longitudinal series of beads on each side, those near the 

 middle converging and smaller. Anterior valve having 18 radial 

 rows of white pustules standing on slight, dark, narrow riblets. Pos- 

 terior valve having the mucro slightly in front of the middle, poste- 

 rior slope concave, with sparsely scattered pustules. 



Interior white, slightly stained under the beaks. Anterior valve 

 having 8, median 1-1, posterior valve 9 slits ; teeth long and sharp ; 

 eaves short and solid. Sinus narrow, supplied with a narrow con- 

 cave-edged lamina, notched at each side. 



Girdle densely clothed with minute chaffy scales, with occasional 

 long corneous hairs (fig. 38). 



Length 11 mill. ; divergence 130. 



Off East Asia. 



"/ Trachydermon" asperior CPR. MS. ; vide Pilsbry, Manual xiv, 

 p. 77. 



The type of this species is a single specimen (Smiths. Inst. Mus. 

 24121) in excellent preservation. Valves i, vii, and viii are detached, 

 the latter two being illustrated on my plate. It is somewhat surpris- 

 ing that Carpenter called this a Trachydermon, for it is an unequi- 

 vocal Chcelopleura in girdle, eaves, sculpture and indeed the whole 

 aspect. It belongs to the group of Ch. gemmea. 



Genus ISCHNOCHITON Gray (Vol. XIV, p. 53). 

 Ischnochiton GRAY and authors, type longicymba. 



Radsiella THIELE, Das Gebiss der Schnecken ii, p. 3G8, for punc- 

 tulatissimus Sowb., concinnus Sowb., capensis Gray, caliginosus Rv., 

 tessellatus Q. & G., rugulatus Sowb. Not Radsiella Pilsbry, Man. 

 Conch, xiv, p. 54, 139 (July 25, 1892). 



Stereoplax THIELE, t. c., p. 383, for " multicosiata " C. B. Ad. 



Rhodoplax THIELE, t. c., p. 384, for squamulosa C. B. Ad. and 

 erythronotus C. B. Ad. 



