202 TONICIA. 



riblets. the riblets sometimes broken into rows of distinct granules. 

 Central areas longitudinally costulate except for a narrow, smooth 

 dorsal band on the latter 6 valves. End valves radially ribbed, 

 with rows of eyes in the intervals. Umbo of tail valve anterior, 

 elevated. 



Interior white, some or all of the valves having a small reddish 

 spot under the apices. Sinus narrow, denticulate. Anterior valve 

 having 8, central 1, posterior valve 10-12 slits; teeth pectinated. 



Girdle yellow or brown, leathery, thin. 



Length 34, breadth 20 mill.; divergence 100-110. 



Callao, Peru. 



C. swainsonii SOWB., P. Z. S. 1832, p. 27 ; Conch. Illustr., f. 5. 

 REEVE, Conch. Icon., t. 7, f. 38. Lopliyrm swainsonii TAP.-CAN. 

 Viag. Magenta, p. 75. 



This species is well differentiated from forms of the elegans group, 

 by the longitudinal ribbing of the entire central areas. The ribs 

 vary much in prominence, however, and in many individuals the 

 riblets of the lateral areas are broken into granules. The color- 

 pattern is similar to that of T. lineolata, but finer. 



T. RUBRIDENS Pilsbry, n. sp. PI. 44, figs. 65, 66, 67. 



Shell oblong, elevated, the dorsal ridge roundly angular, side- 

 slopes straight. Surface smooth. Tawny-brown, sometimes uni- 

 colored, but generally having dotted light rays on lateral areas and 

 end valves, and a dark dorsal band. A light fawn color sometimes 

 predominates over the dark. 



Valves rounded at the front corners, moderately beaked ; sutures 

 not crenulated. 



Lateral areas not perceptibly raised (except on the second valve), 

 sculptured with minute granules sparsely and irregularly scattered, 

 varying much in number ; and along the forward part there is one 

 series of small black eye-dots, becoming an irregularly double series 

 on the lower half of the slope. End valves weakly granulose and 

 having radiating rows of eyes. Central areas entirely smooth except 

 for growth-lines, having no grooves along the dorsal ridge. Beak of 

 tail-valve obtuse, behind the middle. 



Interior of a peculiar red-brown color, the callus of each valve 

 whitish. Sutural-plates thin, red-brown. Sinus delicately dentic- 

 ulate, the area behind it, extending to the beak, transversely 

 wrinkled. Slits in anterior valve 8, central valves 1, posterior valve 



