ISCHNOCHITON. 105 



The passages in brackets of the above diagnosis are Shuttle- 

 worth's interpolations. 



I. LATERITIUS Shuttleworth. Unfigured. 



Shell elliptical-oblong, convex ; brick colored, sparsely maculated 

 with whitish ; end valves subconcentrically lineate and punctate. 

 Median valves not carinated ; central areas irregularly foveolate- 

 irapressed, becoming transversely costulate-subsulcate at the sides; 

 lateral areas subelevated, radiately subsulcate and minutely punc- 

 tate-foveolate. Girdle unicolored red, densely beset with minute 

 flattened scales. Length 12, breadth 6 mill. (Shuttlw.) 



St. Thomas, West Indies. 



Chiton (Ischno chiton) lateritius SHUTTLW., Diagn. n. Moll, in 

 Bern. Mittheil. 1853, p. 75. 



I have not identified this species, of which Shuttleworth writes : 

 I have two specimens. The color is an intense brick-red, both 

 inside and out. It is allied to C. erythronotm C. B. Ad., but differs 

 abundantly in the sculpture and color, and in the less elongated 

 shell. 



4. Group of I. striolcitti*. 



Small species, apparently smooth, but under a lens showing a 

 sculpture of longitudinal riblets or lines of granules on the central 

 areas, interrupted on the lateral areas, which are roughened by 

 peculiar irregular impressions (pi. 18, figs. 54, 55). It is difficult to 

 describe the sculpture of the lateral areas of these species ; it is 

 what Carpenter called "thumby " or " pollicaroid." 



Distribution : Antillean and Panamic provinces. 



Species with striated scale*. 



I. STRIOLATUS Gray. PI. 20, figs. 20-24. 



Shell oblong, moderately arched, the back sometimes distinctly, 

 sometimes scarcely visibly keeled; side slopes convex. Surface 

 showing no sculpture to the naked eye, but having- the lateral areas 

 moderately distinct. Color excessively variable but generally 

 either olive-green or olive-slate colored with white or creamy flecks; 

 or cream-colored, minutely mottled with light brown. The poste- 

 rior edge of each valve is dotted with light and dark, forming a 

 sutural articulation. 



