ISCHNOCHITON. 119 



tion, from the contraction of the epidermal film. Dr. Gould sur- 

 mised that this species ought to be a Lucia, because it came from 

 the Pacific Is. ; but it is a normal Ischnochiton in all respects 

 except the nou-striation of the scales. (Cpr.~) 



I. BISCULPTUS Carpenter, n. sp. 



Shell small, oval ; jugum acute; mucro median, rather elevated ; 

 ashy, maculated with olivaceous. Entire surface minutely granu- 

 lose ; central areas having about 10 distant, acute, subparallel lirse, 

 sometimes subgranose, the interstices wrinkle-decussated. Lateral 

 areas scarcely raised, having distant, small, much raised grains, sub- 

 radiately arranged in 2-4 series, the end valves having 16-20 such 

 series. Interior: posterior valve having 7, central valves 1, ante- 

 rior 10 slits ; teeth rather obtuse, roughened but scarcely pectinated 

 at the margin. Eaves small ; sinus small, deep, smoothly laminate. 

 Girdle rather regularly imbricated with decidedly transverse, con- 

 spicuously striated scales. Length 11, breadth 6 mill. ; divergence 

 120. (Q;r.) 



/ Hong Kong (Stimpson, N. P. E. E.). 



" Chiton f pulcherrimus Sby." GOULD, MS. -f C. (Leptochiton) 

 craticulatus GLD., Otia, p. 117, pars. (Cpr.). 



The shells forming the five species, pulcherrimus, craticulatus, cul- 

 tratus, bisculptus and asperior were included by Dr. Gould under 

 the first two names. They need a careful examination of the 

 details of sculpture, as well as of the mantle scales, in order to sep- 

 arate them. Of these pulcherrimus and bisculptus have the striated 

 scales of Ischnochiton ; craticulatus and cultratus, the strong, smooth 

 scales which belong to Lepidopleurus ; and asperior is intermediate 

 between Trachydermon and Chsetopleura. The decided rugosity of 

 the insertion plates and short eaves of this species form a transition 

 toward Chiton. The whole group appears to have a slight lamina 

 at the sinus, marked oflf by a slit from the sutural wing. (Q?r.) 



7. Group of I. inter stinctus. 



Small, finely granulated shells, the lateral areas radially ribbed. 

 Scales striated. Species of the west coast of North America. 



I. INTERSTINCTUS Gould. PI. 11, figs. 40, 41 ; pi. 21, fig. 39. 



Shell oval-oblong, rather elevated, the dorsal ridge obtusely 

 keeled, side slopes nearly straight. Surface apparently smooth, but 



