506 MAZATLAN UNIVALVES 
character of the epidermis may be relied on, which is very thin, 
rather deciduous, with a very few fine ridges of growth. It is 
further distinguished from all the varieties of A. costellata, by 
its large size, very regular, somewhat inflated growth, sharp 
continued ribs cancellated over the whole surface, and strong 
teeth on the upper portion of the outer lip. Colour principally 
brown with a white band below the suture. The young shell 
has a distinct, somewhat bent canal, and is exquisitely beauti- 
ful. Long. °88, long. spir. ‘47, lat. *4, div. 40°. 
Hab.—Panama & Chiriqui, under stones, Cuming.—Mazatlan ; 
extremely rare ; L’pool Col. 
Tablet 2418 contains a young and the adult specimen. 
646. ANACHIS CosTELLATA, Brod. & Sow. 
Columbella costellata, Brod. & Sow. in Zool. Journ. vol. iv. 
p. 376, (1829.)—Gray in Zool. Beech. Voy. p. 129, pl. 36, 
f. 9.—Sow. in Proce. Zool. Soe. 1832, p. 118.— Mill. Syn. Nov. 
Test. Viv. p. 88.— Ducl. in Chénu, Ill. Conch. pl. 25, 
f. 11, 12.—Sow. Thes. Conch. p. 137, no. 79, pl. 39, f. 147.— 
C. B. Ad. Pan. Shells, p. 84, no. 81. 
(Columbella) Anachis costellata, H. & A. Ad. Gen. i. 184. 
Although early published, this species is not included by 
Deshayes in the An.s. Vért.: by which the student loses the 
very accurate diagnosis which would have been given to this as 
to the other species. The Mazatlan shells divide themselves 
with tolerable accuracy into two sets, the one characterized by 
a coarse lamellar epidermis, the other by one very thin, smooth, 
or rarely scaly, closely adherent, and displaying the rich 
chesnut colour of the shell. The latter are those which agree 
with the figure in Zool. Beech. Voy. They differ from C. 
scalarina in their very much smaller size, chesnut markings, 
flattened whirls, and the adherence of the epidermis. Should 
the epidermal differences prove constant, they may be the best 
characters to recognize the species, as the features recorded by 
Sowerby are subject to great variation. The decussation of 
the interspaces is generally only seen on the spire in the young 
shell ; the spiral stric at the base are sufliciently conspicuous. 
A narrow sp. measures long. ‘52, long. spir. ‘28, lat. °22, div. 34°. 
A broad sp. ‘ st SORE s RS Te Pte oa (ove inet! en 
Hab.—Panama, 1 sp. 16fm., Cuming.—Panama and coast of 
Africa [?] Gray, in Beechey’s Yoyage.—Panama; under 
. 
