LACUNA. 63 



Conch. Diction, p. 194. — Fleming, Brit. Animals, p. 

 299.— Brown, Illust. Conch. G. B. p. 16, pi. 10, f. 35. 

 — DiLLW. Recent Shells, vol. ii. p. 845. — Wood, Index 



Testae, pi. 31, f. 70 Loven, Index Moll. Scandinav. 



p. 22. 

 Lacuna quadrifasciata Tvrt. Zoolog. Journ. vol. iii. p. 191. 



" vincta, TuRT. Zoolog. Journ. vol. iii. p. 192. — Johnston, Berwick 

 Club, vol. i. p. 273. — Macgilliv. Moll. Aberdeen, p. 143. — 

 Brit. Marine Conch, p. xxxviii. (changed from Turlo v. 

 p. 168).— Brown, Illust. Conch. G. B. p. 9, pi. 10, f. 46.— 

 Philippi, Wieg. Arcli. 1836, pt. 1, p. 231, pi. 8, f. 4.— 

 Gould. Invert. Massach. p. 265, f. 178.* — Dekay, New 

 York Moll. p. Ill, f. 119. 

 „ canaUs, Turt. Zoolog. Journ. vol. iii. p. 192. — Brown, Illust. Concli. 



G. B. p. 9, pi. 10, f. 48. 

 „ pertusa, Conrad, Journ. Acad. N. S. Philadel. vol. vi. p. 266, pi. 11, 



f. 19. 

 „ vincta var. ? gracilior, Metcalfe, Brit. Marine Conch, p. xxxviii. f. 86. 

 ' „ divaricala, Loven, Index Moll. Scandinav. p. 23. 

 „ cornea and bifasciata, Brown, 111. Conch. G. B. p. 10, pi. 10, f. 47, 

 44, 45. 

 striata, Brown, 111. Conch. G. B. p. 10, pi. 10, f. 49 (probably). 



A wide amount of difterences is exhibited in the several 

 varieties of this abundant shell ; differences, however, so 

 evidently arising from proportionate modifications of the 

 same normal form, — a criterion we esteem imjiortant in 

 determining the narrow limits between specific and varietal 

 distinction — that in accordance with, and perhaps a little 

 in deference to, the opinion of the great collectors of the 

 present day, whose ample store of specimens in every 

 stage and circumstance of growth, affords them the best 

 of data for arriving at an accurate decision, we have united 

 the vincta, canalis, and quadrifasciata of Montagu under 

 one common appellation. 



In the most characteristic examples of vincta — and such 

 we consider those individuals to be, which in shape are 

 most dissimilar to the other British Lacimae — the form 

 is oblong-conical, passing into ovate-conical, and the shell 

 is thin, transparent, a little glossy, and apparently smooth, 



