506 MAZATIAK UNIVALVES 



character of the epidermis may be relied on, which is very thin, 

 rather deciduous, Mrith 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°. 



Hah. — Panama & Chiriqui, under stones, Cuming. — Mazatlan ; 

 extremely rare ; L'pool Col. 



Tablet 2418 contains a young and the adult specimen. 



646. Akachis costellata, Brod. Sf Soio. 



ColumbeUa costellata, Brod. ^" Sow. in Zool. Joiirn. vol. iv. 



p. 376, (1829.)— (?ray in Zool. Beech. Voy. p. 129, pi. 36, 



f. 9.— Sow. in Broc. Zool. Soc. 1832, p. 118.— Milll. Syn. Nov. 



Test. Viv. p. 88. — Duel, in Clienu, III. Conch, pi. 25, 



f. 11, I2.—S010. Thes. Conch, p. 137, no. 79, pi. 39, f. 147.— 



C. B. Ad. Ban. Shells, p. 84, no. 81. 

 (Columbella) Anachis costellata, S. Sf A. Ad. Gen. i. 184. 



Although early published, this species is not included by 

 Deshayes in the An. s. Vert. : 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 epidennis, 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 difi'erences prove constant, they may be the best 

 characters to recognize the species, as the features recorded by 

 Sowerby are subject to gi-eat variation. The decussation of 

 the interspaces is generally only seen on the spire in the yoimg 

 shcU ; the spiral striae at the base are sufficiently conspicuous. 

 A narrow sp. measures long. "52, long. spir. "23, lat. "22, div. 34 . 

 A broad sp. ,, ,, '65, „ "34, „ *3, „ 40. 



ITai.— Panama, 1 sp. 16 fm., CjmfH^r.— Panama and coast of 



Africa [?] Gray, in Becchey's Voyage.— Panama ; under 



