MAZATLAN UNIVALVES 489 



FAMILY BUCCIJSTID^E. 



Operculum thin, horny, generally subovate, regular : nucleus 

 subcentral, or directed to the anterior outer margin. 



GENUS COLUMBELLA, Lam. 



Columbus, Montf. Peristera, Hqfin. 



Columbella, pars solum, auct. : v. Nitidella et Anachis. 



615. COLUMBELLA MAJOE, Sow. 



rroc/Zool. Soc. 1832, p. U9. Mull. Syn. Nov. Test. Viv. 

 p. 90. Sow. Thes. Conch, p. 110, no. 2. pi. 36, f. 3, 4, 6. 

 Desk, in Lam. An. s. Vert. vol. x. p. 266 note, 274, no. 19. 

 Trait. Mem. pi. 120, f. 11, 12. Mice, in Zeit.f. Mai. 1847, 

 p. 182, no. 19. C. S. Ad. Pan. Shells, p. 93, no. 94. 

 C. strombiformis, var. Kien. Icon. Conch, p. 4, pi. 1, f. 1, a. 

 Adol. ? = C. paytalida, (Duel.) Kien. Icon. Conch, p. 5, no. 3, 



pl.l,f.2.* ' 



P=C. gibbosa, Vol. in Eumb. Rec. Obs. vol. ii. p. 331. Duel. 

 in Chenu, III. Conch, pi. 5, f. 5, ?6. 



This fine and typical species is clothed with a very thick 

 olive epidermis, lying in laminae of growth ; of which those 

 above the periphery are very finely serrated by spiral lines, 

 and those below are somewhat irregularly shaggy. The apex 

 is often red, sometimes white. The majority of living speci- 

 mens are for the most part free from incrustations. Along 

 with other species, it varies in the number of labral teeth, and 

 in the amount of shouldering near the suture. 



The individuals of this species present remarkable differences 

 in their opercula. In the normal state, of which many hun- 

 dreds have been examined, it is intermediate between Purpura 

 and Buccinum, resembling that of Columbella rustica as figured 

 by Duel., Mon. pi. 3, f. 10 b, or lopas sertum, If. fy A. Ad. 

 Gen. vol. i. pi. 13, f. 4 a. It is thin, light horn-coloured, with 

 an ill-defined purple-brown stain in a radiating central triangle ; 

 with coarse strise of growth, ovate, more or less angulated at 

 the vertex, which is generally decollated, and situated towards 

 the base of the labrum. Sometimes the nucleus is close to the 

 basal margin, sometimes nearer the middle ; the operculum 



* It is difficult to say whether this is a half-formed C. major, or a C. fuscata, 

 as the refercnceto C. rustica, Sow. Gen. f. 3 implies. The C. fuscata is the C. 

 meleagris (Duel.) of Kiener, who figures the true C. rustica with a finely cancel- 

 lated velvety epidermis. 



