MAZATLAN UNIVALVES 223 



Emarginula. The plan of cancellation and the form of the slit 

 differ somewhat in the specimens, but probably not specifically. 

 The smallest shell, though scarcely '04 in length, displays a 

 channel "01 long, as in the adult. The largest measures 

 long. '125, lat. '07, alt. '035. 



Hob. Mazatlan ; on Spondylus calcifer, extremely rare ; 

 JL'pool Col. 



Tablet 1080 contains 3 sp. of different ages. 



FAMILY HALIOTID.E. 



JSTihil. 



FAMILY TEOCHID^. 

 GENUS CALLOPOMA, Gray. 



Fig. Moll. An. p. 87, no. 5 :PMl. Handb. Condi, p. 206 : 



H. fy A. Ad. Gen. i. 395. 

 Turbo, sp., auct. Distinguished by the extreme complexity 



of the operculum : v. infra. 



I 282. CALLOPOMA (TUEBO) FLUCTUOSUM, Mawe. 



Turbo fluctuosus, Gray in Wood Suppl. p. 20, pi. 6, no. 44. 



Mice. Zeit.f. Mai. 1847, p. 179, no. 8: do. 1850, p. 170, 



no. 25. Kust. Chemn. p. 60, no. 55, pi. 14, f. 3, 4 c. 

 Turbo fluctuatus, Eve. Proc. Zool. Soc. 1848, p. 52 i Conch. Ic. 



sp. 34, pi. 8, no. 34. 

 Trochus (Turbo) Fokkesii, Jonas, in Phil. AbUld. no. 1, pi. 2, 



f. 1, 10. Midden. Mai. Ross. pt. ii. p. 86, no. 13. 

 CaUopoma fluctuatum, H. fy A. Ad. Gen. i. 395, pi. 43, f. 7, la, 7b. 

 Comp. Callopoma ? fluctuatum, var. depressum, Proc. Zool. 



Soc. 1855. ( = Turbo f. var. Rve. Condi. Ic. pi. 9, f. 3 c.) = Turbo 



funiculosus, Kien. Icon. Conch, pi. 30, f. 1. 



Almost all the numerous specimens of this beautiful shell 

 fell victims, after I had first examined them, to the grindstone 

 and acid. The exquisitely beautiful opercula were however 

 thrown to one side as useless, and so preserved. These are flat 

 and covered with a dark horny layer inside, displaying about 6 

 whirls. Outside with a broad central spiral callus, white and 

 granular, concealing the umbilicus, with extremely minute 

 pustules over the surface, sometimes with a few sharp prickles. 

 A deeply cut groove surrounds the callus, followed by a green 



