ISCHNOCHITON. 131 



Interstices transversely wrinkled. Lateral areas having close, little 

 elevated graniferous riblets, 4 in young, 8 to 10 in adult individuals; 

 anterior valve having about 50 such riblets. Interior: posterior 

 valve having 11, central valves 1, anterior valve 10 slits; teeth 

 short, not very acute, outside and at the margins in front rugulose, 

 almost pectinated in front. Eaves small, obtuse; sinus short, 

 narrow, slightly denticulate. Girdle irregularly, closely imbricated 

 with small, smooth, solid scales. 



Length 25, breadth 15 mill. ; divergence 93. (Cpr.~) 



China Seas, or Japan (Stimpson, N. P. E. E. ; 1 specimen in Mus. 

 Smithsonian.) 



Chiton (Leptochitoii) craticulatus GOULD, Proc. Bost. Soc. N. H. 

 vii, p. 161, Dec. 1859; Otia Conch., p. 117. Lepidopleurus cratic- 

 ulatus CPR., MS. 



Dr. Gould appears from his diagnosis to have had several species 

 under his eye when he wrote the description of this species. From his 

 calling it a Leptochiton, he might have looked at the minute, chaffy 

 scales of Trackydermon asperior ; when he wrote of long striated 

 scales, he was probably observing Ischnochiton bisculptus. Again 

 when he noted the great variation of the ridges (from 4 to 8), he 

 probably had under his eye both I. cultratus and the species above 

 described. Of the four, the balance of characters inclines me to 

 retain the name for the shell last mentioned, although only one spec- 

 imen was returned of it, mixed with the other three. Outside, the 

 species is recognized by the solid smooth scales, and details of 

 sculpture; inside by the blunt, somewhat rugulose teeth, which (in 

 part of the anterior valve) are almost pectinate. ( Cpr.^) 

 I. CULTRATUS Carpenter, n. sp. Unfigured, 



Shell similar to " L. craticulatus"; mucro central, planate, but 

 central areas having about 14 to 20 very acute, strongly developed 

 subparallel lirse, becoming less acute, somewhat obsolete, on the dorsal 

 ridge ; sutures elegantly pectinated, interstices cancellated with small 

 wrinkles; lateral areas having 4 low, graniferous lirulse, and a 

 fifth line of granules at the sutures, the grains sparse, small, but 

 strongly projecting. Posterior valve having about 18 similar lirulse, 

 anterior valve 24. Interior: posterior valve having 9, central 

 valves 1, anterior valve 8 slits ; teeth acute ; eaves projecting ; sinus 

 small, deep, sensibly laminated, smooth. Girdle regularly imbri- 

 cated with flat, smooth scales. ( Qor.) 



.Length 27, breadth 17 mill. 



