158 HELICID^. 



This shell varies in shape, size, and colour, being 

 sometimes transparent greenish white, from want of 

 substance and colouring matter. It also varies in 

 having one or two additional small teeth in the peri- 

 stome alternately with the larger ones. 



9. AcHATiNA Lam. (Agate Shell.) 



Animal like Bulimus, with four tentacles and an 

 oval-oblong or somewhat cylindrical shell, ob- 

 tuse at the tip ; aperture longitudinal, oval ; the 

 outer lip thin, without any internal rib, and 

 never reflected ; pillar smooth, simple, truncate 

 in front. 



The abruptly truncated termination of the pillar 

 or inner lip of the shell will immediately distinguish 

 this genus from Bulimus, to which it is in other cha- 

 racters so nearly allied. The only British species 

 forms a very distinct section, perhaps genus, from 

 the larger exotic kinds. 



a. Shell turreted, polished, transparent; mouth oblong, 

 rather narrow ; upper tentacles subulate, blunt, 

 eyeless. (Styloides. Acicula Nilson.) 



69. 1. AcHATiNA Acicula. Needle Agate Shell. — 

 Shell slender, smooth, polished, white, with six 

 flat volutions ; the lower one as long as all the 

 others; mouth elliptical, (t. 6. f. 77.) 



Achatina Acicula. Lam. vi. p. 133. ; Rossm. Icon. x. f. G58. 

 Forbes and Hanley, B. M. iv. 130. t. 128. f. 4. — Bulimus 

 Acicula. Brug. E. M. 1. 31 1.; Drap. p. 75. t. 4. f. 2-5, 26. 

 Brard, p. 100. t. 3. f. 21. — Buccinum terrestre. Mont. T. B 

 p. 248. t. 8. f. 3. — Buccinum Acicula. 3IiUler, Verm, ii 



