MAZATLAN UNIVALVES 489 
Famity BUCCINIDA. 
Operculum thin, horny, generally subovate, regular : nucleus 
subcentral, or directed to the anterior outer margin. 
Genus COLUMBELLA, Lam. 
Columbus, Jfongfi—Peristera, Rafin. 
Columbella, pars sclum, auct.: v. Nitidella ef Anachis. 
615. CoLUMBELLA MaAJoR, Sow. 
Proc. Zool. Soc. 1832, p. 119.— Mill. Syn. Nov. Test. Viv. 
p. 90.—Sow. Thes. Conch. p. 110, no. 2. pl. 36, f. 3, 4, 6.— 
Desh. in Lam. An. s. Vert. vol. x. p. 266 note, 274, no. 19.— 
Trait. Elem. pl. 120, f. 11, 12.—Mzke. in Zeit. f. Mal. 1847, 
p. 182, no. 19.—C. B. Ad. Pan. Shells, p. 93, no. 94. 
C. strombiformis, var. Kien. Icon. Conch. p. 4, pi. 1, f. 1, a. 
Adol. ?=C. paytalida, (Ducl.) Kien. Icon. Conch. p. 5, no. 3, 
pil, t2™ 
P=C. gibbosa, Val. in Humb. Rec. Obs. vol. u. p. 331.—Duel. 
in. Chénu, Iii. Conch. pl. 5, f. 5, ?6. 
This fine and typical species is clothed with avery thick 
olive epidermis, lying in lamine 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 Buecinum, resembling that of Columbella rustica as figured 
by Ducl., Mon. pl. 3, f.106, or Topas sertum, A. & A. Ad. 
Gen. vol. i. pl. 13, f. 4a. It is thin, light hornecoloured, with 
an ill-defined purple-brown stain in a radiating central triangle ; 
with coarse strie 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 referenceto C. rustica, Sow. Gen. f. 3implies. The C. fuscata is the C. 
meleagris (Ducl.) of Kiener, who figures the true C. rustica with a finely cancel- 
lated velvety epidermis. 
