TRIVIA. 199 



T. OVULATA. Lam. PL 21, figs. 69, 70. 



Differs from the preceding in being smooth throughout ; the 

 teeth on the inner lip are very small. Length, -7-'9 inch. 



Cape of Good Hope. 

 T. COSTATA, Gmel. PL 21 , figs. 71,72. 



Differs from G. oniscus in having rather finer ribs, and in the 

 absence of a dorsal impression. Length, '6--7 inch. 



West Indies (Krebs), Cape of Good Hope (?) 



This species was described by Gray as T. carnea, and by- 

 Wood as G. rosea. 



- T. VESICULARIS, Gask. PL 21, figs. 73, 74. 



Much smaller than G. oniscus, dorsal striae finer, more numer- 

 ous and regular ; no dorsal impression. Length, -5 inch. 



Cape of Good Hope. 



Group B. Shell thick, usually margined, aperture narrow and 

 more or less central. 



a. Having a dorsal impression. 



* Shell white. 

 T. SULCATA, Gask. PL 21, figs. 75, 76. 



Ventricose, ribs coarse, prominent, spire perceptible, inner lip 

 ending posteriorly in a sharp edge. Length, -45 inch. 



Manilla. 

 T. CICATROSA, Sowb. PL 21, figs. 77, 78. 



Subglobose, outer lip expanded posteriorly, dorsal impression 

 short and very deep. Length, '3 inch. 



Hab. (?) 

 T. NIVEA, Gray. PL 21, figs. 80, 81. 



Globose, extremities very obtuse, ribs narrow, wrinkled. 



Length, -35-'45 inch. 



West Indies. 



There has been some confusion regarding this species, caused 

 partly by the name " nivea " having been first given by Dr. Gray 

 to a shell which* was afterwards recognized us a white variety of 

 C. turdus. Later he adopted the same name from Solander MSS. 

 for what the eminent conchologist Gaskoin, as well as myself, 

 believed to be Lamarck's oryza ; but the characters given, and 



