ODOSTOMIA. 



121 



the next species (O. albella) this diflPers in colour, tex- 

 ture, abrupt termination of the spire, greater convexity 

 of the whorls, contraction of the outer lip, the presence 

 of an umbilicus, and prominence of the tooth. 



6. O. albel'la"^, Loven. 



Turhonilla albella, Lot. lud. Moll. Scand. p. 19. 0. rissoides, rar. (pro- 

 yisionally), F. & H. iii. p. 286, pi. xcvi. f. 5. 



Body creamcolour, streaked with sulphur, sometimes clear 

 white, gelatinous, and of a granular texture under a high 

 magnifying-power: snout or mentum narrow, not always ex- 

 tended beyond the foot : tentacles leaf-like, rather short and 

 thick : eyes small, placed close together : foot short, squarisli 

 in front, narrow or constricted in the middle, broader and 

 bluntly pointed behind ; sole edged with yellow. 



Shell cylindi'o -conical, rather thin, semi transparent, and 

 of a dullish hue : sculpture, as in 0. rissoides ; the young 

 exhibit faint spiral strice under a microscope: colour pale 

 yellowish-white, variegated in fresh specimens by reddisli- 

 brown blotches on the upper part, which represent the dried 

 remains of the animal : sp/re tapering to a blunt point ; the 

 apex shows distinctly the reversed and inverted embryonic 

 nucleus : luhorls 5-i), rounded but somewhat compressed, 

 gradually enlarging ; the last occupies about three-fifths of 

 the shell : suture shallow but incised ; below it each whorl 

 appears encircled by a narrow band, as in 0. rissoides : mouth 

 oval, contracted on the outer side, slightly expanded and ob- 

 tusely angulated at the base ; it usually equals in length one- 

 third of the spire : outer lip slightly curved : inner lip not 

 much spread on the pillar, nor united above with the outer 

 lip, thickened and slightly reflected on the lower side : umhi- 

 licus none, although there is sometimes a narrow chink behind 

 the inner lip : tooth small, retired and nearly hidden within 

 the pillar : operculum yellowish, marked with white down the 

 spire, finely and deeply striated in the line of growth, the 

 strife becoming very close towards the nucleus ; flap not stri- 

 ated ; groove and ridge as in 0. conoid ea ; spire very short, 

 indistinct, and nearly terminal. L. 0-115. B. 0-05. 



Habitat : Underneath loose stones at low-water mark 



* Whitish ; properly albida. 

 VOL. IV. G 



