222 PNEUMONOBRANCHIATA. 



cylindrical, blunt, or truncated tentacles, at the base of 

 which, between, or nearly behind them, are placed two 

 very conspicuous approximating black eyes. (p. 219. 

 f. 1, 2.) (Montagu, T. B. 340. ; Sturm, 1. 1. f. 3.) 



Shell hardly the tenth of an inch long, conic, white, 

 shining, with a yellowish cast, transparent; spire 

 composed of five rounded volutions, very finely striate 

 longitudinally, and ending rather obtusely ; aperture 

 semioval or rather ear-shaped, rounded at both the 

 ends, with two teeth on the pillar, and sometimes a 

 small one above the others ; the margin thick, and in 

 the middle of the outer lip a thick tooth-like protu- 

 berance. 



This common species was first noticed by Mr. Boys 

 (Test. Min.JRar. f.5L). 



Mr. Jeffreys has erroneously referred the Turbo 

 tridens to this genus, under the name of Carychium 

 politum. (Linn. Trans, xvi. 363.) 



2. ACME Hartmann. 



Shell subcylindrical, with a blunt tip ; mouth ovate, 

 simple, outer lip simple, thin, slightly reflexed over 

 the pillar, forming a slight perforation. 



Animal with two long contractile slender tentacles, 

 between which and the eyes, at their hinder base, 

 are two jagged blackish spots. (See p. 219. f. 3.) 



Dr. Turton (Manual, ed. 1. p. 83.) appears to have 

 considered the spot at the base of the tentacles as the 

 rudiment of a lower pair. Dr. Hartmann (Sturm, 

 Fauna, 1. 1. f. 4.) describes the tentacles as retractile; 

 but he uses the same term to describe the tentacles of 

 Cyclostoma and Carychium, which agree with these in 



