LACUNA. 59 



Trans. Linn. Soc. vol. viii. p. 205. — Turt. Conch. Diction. 

 p. 57. 

 Heli.i: lacuna, MoNT. Test. Brit. p. 428, pi. 13, f. 6.— Maton and Rack. Trans. 

 Linn. Soc. vol. viii. p. 20L — Dillvv. Recent Shells, vol. ii- 

 p. 917._WooD, Index Testae, pi. 33, f. 70. 

 Nerita rufa, var. Mont. Test. Brit. Suppl. p. 15L 

 Turbo lacuna, TuRT. Conch. Diction, p. 193, f. 87, 88, 89. 



„ puteolus, Turt. Conch. Diction, p. 193, f. 90, 91. 

 Lacuna „ Turt. Zoolog. Joiirn. vol. iii. p. 191. — Brit. Marine Conch, 

 p. xxxviii. 

 „ Montacuti, Turt. Zoolog. Journ. vol. iii. p. 191. 

 Turho fasciatus, Fleming, Brit. Animals, p. 300. 

 Natica lacuna, Fleming, Brit. Animals, p. 320. — Brit. Marine Conch, p. 150. — 



PoTiEZ and Mich. Galerie Douai, Moll. vol. i. p. 292. 

 Lacuna fasciata, Macgilliv. Moll. Aberdeens. p. 145. — Brit. Marhie Conch, 

 p. 256, f. 84. — Brown, lUust. Conch. G. B. p. 128, pi. 10, 

 f. 54 (changed from Pkasianella fasciata, p. 10). 

 „ sulcata, Macgilliv. Moll. Aberdeens. p. 146 (fide Jeii'reys from type). 

 „ Montagui, Brown, lUust. Conch. G. B. p. 128, pi. 57, f. 8. 



The members of the genus Lacuna require a studious 

 examination of long suites of examples collected from 

 various localities, in order to arrive at just conclusions 

 respecting the natural limits of each species. Our group- 

 ing together the very dissimilar forms that we have 

 included under the name of puteolus, is the result of such 

 an examination, and is forced upon us, contrary to our 

 preconceived ideas, by the observation of numerous con- 

 necting links between the several varieties. We propose 

 to describe at large the typical form (the L. puteolus of 

 the " Zoological Journal," Turbo lacuna of " Turton's 

 Dictionary'"), and then to indicate the more peculiar 

 aberrations from its ordinary characteristics. 



The shape is nearly globular, and the shell, when adult, 

 is comparatively strong, and hence not particularly trans- 

 lucent. It is covered with a thin dull yellowish horn- 

 coloured skin, beneath which the surface is either of an 

 uniform livid white, for the most part changing to an 

 obscure violet upon the spire, or else is alternately marked 



