CHITON. 187 



C. rusticus DH., Moll. Reun., p. 39, t. 6, f. 1-3. CPU., MS. ii, p. 

 25. C. (Lepidopleurus) rmticus MTS. in Mobius' Reise nach Mauri- 

 tius, p. 300. 



This species has considerable resemblance to C. nigrovirens, but 

 the lateral areas and end valves are less strongly sculptured and the 

 longitudinal riblets are lacking on the central areas except at the 

 diagonal lines. The above description is from Carpenter's MS. 



C. ANGUSTICOSTATUS Quoy & Gaimard. PL 31, figs. 37, 38. 



Shell ovate, wide, little elevated, depressed behind by the prom- 

 inence of the anterior valve. The third to the seventh valves are 

 excessively narrow, arcuated behind, with a little median projection, 

 which contributes to form a dorsal carina. The last valve is the 

 largest of all, nearly orbicular ; the second valve is next in size, the 

 intermediate valves being about equal. Sutural plates narrow, 

 separated by a wide, flat, sinus ; insertion-plates denticulate. The 

 end valves have striated teeth. The entire interior is a pretty green ; 

 and this we suppose to be the color of the outside, but it is eroded. 

 We think it is striated like our C. viridis. The girdle is scaly, the 



scales oval. Length 22, width 16, alt. 8 mill. 



Isle of France. 



C. angmticostatus Q. & G., Voy. Astrol. iii, p. 398, t. 73, f. 4, 4'. 



The entire substance of Quoy's description is rather freely trans- 

 lated in the above paragraph. It is very likely that this is merely a 

 greatly worn specimen of C. pellisserpentis Q. & G. 



C. NIGROVIRENS Blainville. PI. 31, figs. 41, 42- (enlarged.) 



Shell ovate, moderately elevated, the dorsal ridge obtuse ; black- 

 ish. Mucro in front of the middle, little raised, the slope behind it 

 straight. 



' Valves obtusely beaked ; entire surface minutely quincuncially 

 granulated ; jugal area smooth, often eroded ; central areas having 

 about 30 delicate lirulse on each side, parallel to the dorsal ridge, 

 sometimes eroded ; lateral areas moderately raised, having 6 to 8 

 delicate granulose riblets, the intervals flat. 



Interior: anterior valve having 12, central valves 1, posterior 

 valve 14 slits ; teeth short, obtuse, coarsely pectinated ; eaves 

 small; sinus wide, flat, 12-toothed. 



Girdle covered with solid, smooth, large and rounded imbricating 

 scales. Length 17J, breadth 10 mill.; divergence 117. 



Cape of Good Hope. 



