MAZATLAN UNIVALVES 507 
stones near low water mark, rare; C. B. Adams.—Mazatlan ; 
very rare; L’pool Col. 
Tablet 2419 contains 3 sp. narrow.—2420, 3 do. broader.— 
2421, 2 sp. one with operculum, the other after the acid process. 
646, (b.) ANACHIS (PCOSTELLATA, va.) PACHYDERMA. 
A. t. “A. costellate” simillimd, sed plerumque latiore, fusco- 
purpurea, albido fasciaté et in tuberculis maculata ; epidermide 
solidd, rugis incrementi confertis ornatd, haud valde adherente ; 
operculo elongato, subarcuato, scabriusculo, apice terminali 
sepe decollato. 
Comp. Columbella varia, Sow. in Proc. Zool. Soc. 1832, p. 116.— 
Miill. Syn. Nov. Test. Viv. p. 86.—Sow. Thes. Conch. p. 180, 
no. 54, pl. 39, f. 116-7.—Desh. in Lam. An. s. Vert. vol. x. 
p. 282, no. 31.—C. B. Ad. Pan. Shells, p. 100, no. 105.— 
=(Columbella) Anachis varia, #. gf A. Ad, Gen. 1. 184. 
It might be thought that the true A. costellata is this shell 
with the outer part of the epidermis rubbed off; but in this 
form, when the epidermis comes off, it leaves the dark purplish 
brown surface of the shell itself, not the close thin skin of the 
chesnut-stained A. costellata. These shells were regarded by 
an eminent authority as one of the many varieties of A. varia.* 
They appear however much more nearly related to A. costel- 
lata, from which the operculum does not perceptibly differ. 
This shell, like A. coste!lata, is more or less turrited, sometimes 
obese; with ribs more or less numerous, more or less waved, 
more or less produced towards the base; interstices more or 
less cancellated by spiral strie. The flattening of the middle 
of the lip often gives the ribs the appearance of being slightly 
tubercular both above and below. Colour purple brown, 
more or less dark and spotted or banded with white. The 
best character is the epidermis, which is thick, lying in trans- 
verse layers as in C. major, but coarser in proportion, dark 
green. A broad sp. measures long. °66, long. spir. °34, lat. °32, 
div. 40°. 
_ Hab.—Mazatlan ; rare; L’pool Col. 
Tablet 2422 contains 6 sp. in different stages.—2423, 1 sp. 
with operculum in situ, and one separate operculum. 
_ * The Col. terpsichore of Menke may belong to this species, though his 
diagnosis appears to apply better to OC, coronata,. 
