CERATOZONA. 291 



The valves are strong, and when not eroded they are somewhat 

 leaked. Lateral areas hardly raised, but defined by a strong . 

 rounded rib, sometimes with a lower wide rib behind ; having a 

 sculpture of irregular wavy wrinkles over ribs and interval, and 

 also upon the sides of the central areas. Head-valve having about 

 11 low radiating ribs and superficially waved concentrically. Tail 

 valve rather depressed with a subcentral, slightly projecting mucro, 

 the area behind it obsoletely radiated. 



Interior blue-green, varying in intensity. Sutural plates moder- 

 ate, separated by a rather wide smooth sinus. Anterior valve 

 having 7-10 slits, the teeth long, acute, slightly rugose outside and 

 denticulate at the edge, generally thickened or propped very strongly 

 along the slits ; central valves with 1 slit, the teeth much thickened 

 at the edges of the slit ; posterior valve having 8-10 slits, the teeth 

 much shorter and blunter than in front, wedge-shaped, denticulate 

 at the edge, not perceptibly propped or thickened along the slits, 

 Eaves very narrow, having a single series of pores along the bases 

 of the teeth. 



Girdle very tenacious, rather wide, yellowish, armed with numer- 

 ous corneous, yellow rather long and pointed spines, most numerous 

 around the edge, and in most specimens showing a bunch of several 

 at each suture ; among these larger spines, slender flexible beards 

 are scattered (fig. 35). 



Length 40, breadth 25 mill. ; generally smaller. 



Jupiter Inlet, east coast of Florida (G. W. Webster et al.) to 

 .Jamaica (C. B. Ad., Johnson & Fox) ; Porto Rico (Blauner) ; St. 

 Vincent and Trinidad (Guilding). 



Chiton rugosus (Gray) SOWERBY, Conchol. Illustr. no. 6, fig. 49, 

 (1841 ?). REEVE, Conch. Icon., t. 18, f. 115 (April 1847). CMow- 

 (Chcetopleura) rugosa Sowb, SHUTTL., Bern. Mittheil. 1853, p. 78. 

 Chiton squalidus C. B. Ad., Proc. Bost. Soc. Nat. Hist., ii, p. 8, 

 (Jan. 1845). Chiton guildingii REEVE, Conch. Icon., t. 21, f. 138 

 (May, 1847). Ceratophorus guildingi CPR. Ceratozona guildingi 

 DALL, Catal. Mar. Moll., S. E. U. S. p. 172. Ch. bicolor (C. B. Ad.) 

 GRAY, P. Z. S. 1847, p. 67. 



This species is not likely to be confused with any except the next. 

 The valves are rather strong and blue-green inside, sometimes very 

 pale. The girdle is of a conspicuous horny yellow color when 

 scrubbed as in most cabinet specimens, but is dull and dark in the 

 natural condition. The horny, curved bristles are both fine and 



