158 CHITON. 



C. MARMORATUS Gmelin. PI. 34, figs. 72, 73, 74, 75, 76. 



Shell oval, rather elevated, the dorsal ridge varying from roundly- 

 angular to distinctly carinated; side-slopes convex or straight. Sur- 

 face smooth, polished. Color varying from olive to dark brown or 

 purple-brown, variously marked with darker spots or blotches and 

 light longitudinal stripes or lines. 



The lateral areas are a little raised ; the whole surface showing a 

 very minute quincuncial pattern of granulation under the lens, and 

 marked with inconspicuous growth-lines. Mucro close to the front 

 edge of the tail-valve, as in C. Icevigatus. 



Interior blue-green, each valve often having darker or olive pos- 

 terior rays. Sinus deep, angular, having a jagged convex row of 

 denticles, half as long as a sutural-plate. Anterior valve having 11- 

 14, central valves 1, posterior valve 13-17 slits; teeth deeply finely 

 pectinated. Eaves, slit-rays and triangle behind the jugal sinus 

 very porous. 



Girdle alternately blotched with green and light blue. 



Length 56, breadth 32 mill. 



Length 48, breadth 26 mill. 



Texas (Dall) ; Bermuda (Heilprin) ; Jamaica (Cpr.) ; Cuba ; St. 

 Thomas (Swift) ; St. Croix ; St. Vincent (Sharp) ; Barbados (Rush) ; 

 and Carthagena, U. S. Columbia (Krebs.) 



Chiton marmoratus GMEL., Syst. Nat. xiii, p. 3205. (Chiton 

 marmoreus CHEMNITZ, Conchyl. Cab. viii, p. 282, t. 95, f. 803-805. 

 Not C. marmoreus REEVE). C. marmoratus SOWB., Conch. Illustr., 

 f. 148-150. REEVE, Conch. Icon., f. 6. SHUTTLW., Bern. Mittheil. 

 1853, p. 74. DALL, Cat. Moll. S.-E. U. S., p. 172.^0. scarabceus 

 REEVE, Conch. Icon., t. 12, f. 66. 



This species is excessively variable, but with all its variety I have 

 seen no specimens having the pattern of the West Mexican C. 

 IcKvigatus and articulatus. The following color-patterns are 

 commonly met: 



1. Entire surface of valves blackish-brown. This is not an 

 uncommon form, being the C. scarabceus of Reeve. 



2. Olive, with fine flecks and lines of whitish, becoming confluent 

 toward the middle. 



3. Either purple-brown or olive, having longitudinal zebra-like 

 stripes on the side-slopes. 



