MAZATLAN UNIVALVES 481 



minute spiral strise. The operculum when perfect presents 

 the remarkable feature of a finely plaited border round the 

 labral external margin. An unusually elevated specimen 

 measures long. 1*23, long. spir. *36, lat. '92, div. 80. 



A normal sp. 1*2, '27, 1'06, ,,100. 



A depressed sp. '84, *05, "86, 170. 



Hah. Mazatlan, 1 sp. Botta. Charles Is., Galapagos ; under 

 stones at low water ; Coming. Taboga ; very rare, same 

 station, and in crevices of rocks near low water mark ; 

 C. B. Adams. Mazatlan; rare, generally encrusted with 

 coralline ; L'pool Col. 



Tablet 2252 contains an adult sp. with Bryozoa, remarkable 

 for a shagreening of the surface, and (in this specimen alone) 

 for a long process from the labrum not seen afterwards. The 

 normal portion displays a sculpture which may develop into 

 P. muricata. 



Tablet 2253 contains 3 sp. elevated. 2254, 3 do. normal. 

 2255, 3 do. depressed. 2256, 1 sp. with operculum, and one 

 separate operculum. 



GENUS CUMA, Humph. 



Swains. Treat. 1840, p. 307 : H. $ A. Ad. Gen. vol. i. p. 133. 

 A convenient, though not very distinctly denned group of 

 Purpurse auct. The plait in the typical species, Cuma tectum, 

 (S. W. Mexico, P. P. C.) does not appear of more generic 

 importance than the fold in Purpura columellaris. 



* 609. CUMA KIOSQUIFOEMIS, Duel. 



Purpura kiosquiformis, Duel, in Ann. Sc. Nat. vol. xxvi. p. 107, 

 pi. 1, f. 5, 1832. Kien. Icon. Conch, p. 59, pi. 15, f. 40. 

 Desh. in Lam. An. s. Vert. vol. x. p. 96, no. 60.JZyd. fr 

 Soul. Voy. Bon. Moll. pi. 39, f. 23-5 : B. M. Cat. no. 194, 

 p. 24. Rve. Conch. Ic. pi. 7, f. 31, var. Gray, Fig. Moll. 

 An. pi. 87 a, f. 6. C. B. Ad. Pan. Shells, p. 77, no. 71. 



Var. = P. scalariformis, DOrl. B. M. Cat. Moll. p. 41, no. 359 : 

 (? = P. s., Lam. An. s. Vert. vol. x. p. 73, no. 20). = Purpura, 

 sp. ind., C. B. Ad. loc. cit. p. 78, no. 72. 



Cuma kiosquiformis, H. fy A. Ad. Gen. i. 134 ; pi. 14, f. 3. 

 This remarkably variable shell is sometimes short and angular 



like the Turbinelloid C. tectum : sometimes with the periphery 



Feb. 1^7. ss 



