196 TONICIA. 



outside and at edge. Sinus square, denticulate ; sutural-plates and 

 insertion-plates white. 



Girdle leathery, thin, yellowish-green, naked. 



Length 34, breadth 20 mill. 



Length 50, breadth 33 mill. ; divergence 115. 



Pearl Island, Bay of Panama (Cuming, et al) ; Mazatlan 

 (Reigen.) 



Chiton crenulatus BROD., P. Z. S. 1832, p. 27. SOWERBY, Conch. 

 Illustr., f. 43. REEVE, Conch. Icon., no. 29, t. 6, f. 39 (error for 29). 

 "/ Tonwia" forbesii CPR., Mazatlan Catal., p. 193 (1856.) 



This species is readily distinguished from the other West Amer- 

 ican forms by the greater width of the lateral bands of eyes, the 

 crenulated sutures, and the beautiful sculpture of the central areas. 

 The second valve is not so prominent as in most species of Tonicia, 

 and it is sculptured like the other intermediate valves. 



T. ELEGANS Frembly. PL 41, figs. 22, 23, 24 ; pi. 42, figs. 31, 32, 



33, 34, 35. 



Shell elliptical-oblong, not much elevated, the dorsal ridge 

 rounded, side-slopes straightened. Color umber-brown at the sides, 

 becoming chestnut in the middle, delicately and peculiarly speckled 

 and blotched and streaked with buff or buff-white. 



Lateral areas hardly raised, but separated from the central areas 

 by an obtuse diagonal ridge bearing a series of low tubercles, some- 

 times subobsolete ; sculptured with subradiating rows of small gran- 

 ules, and showing a band of irregularly placed black eyes on the for- 

 ward part. Central area of second valve having in the middle, a 

 keel or a group of lirae ; central areas of the other valves having a nar- 

 row smooth dorsal band with several longitudinal furrows on each side 

 of it; and at the sides there are longitudinal diverging delicate rows 

 of granules. End valves radially subgranulate, and crowded with 

 eye-spots subradially arranged. Mucro in front of the middle, 

 moderately elevated. 



Interior porcelain white, with a spot or " V " of red-brown under 

 the beak of each valve. Sinus flat, distinctly but finely denticulate. 

 Slits short, in the anterior valve 8, in the central 1, in the posterior 

 valve 9-12 ; teeth blunt, long and very finely, deeply pectinated out- 

 side ; slit-rays regularly puncticulate. 



Girdle naked, leathery, of a chestnut-yellow color. 



Length 48, breadth 32 mill. ; divergence 125. 



Callao to Valparaiso. 



