TROCHUS. 519 



front, and as if villose at the edges. The operculum is 

 bright yellow. Loven represents the central denticle in 

 the tongue of this species as greatly enlarged below and 

 narrowly contracted beneath the slightly-incurved but not 

 mucronated apex, and the laterals as being very strongly 

 hooked. 



Abundant everywhere on all our coasts, living among 

 fuci on the lower belt between tide-marks, very plentiful 

 in the laminarian zone, and occasionally occurring as deep 

 as fifteen or even twenty fathoms. It varies much, and a 

 form is rarely found which may prove to be a hybrid 

 between this and the last. It ranges northwards to the 

 shores of Finmark, and southwards to the coasts of Spain. 

 It occurs fossil in the red crag and pleistocene deposits. 

 On some parts of our coast it is called the Dog- 

 Periwinlde. 



T. umbilicatus, Montagu. 



Orbicular-conoid, generally perforated ; spiral sculpture not 

 granular, no marginal belt ; painted with purplish red linear 

 stripes on a yellowish or greenish white ground. 



Plate LXVI. fig. 1 to 4, as umbilicalis. 



Trockw umbilicaris, Pexn. (not Linn, nor Lam.) Brit. Zool. ed. 4, vol. iv. 

 p. 126, pi. 80, f. 106. 

 „ umbilicalis, Da Costa, Brit. Conch, p. 46, pi. 3, f. 4. 

 „ oblique radiatus, Chbmn. Conch. Cab. vol. v. p. 117, pi. 171, f. 1685 



(not well). 

 „ cinerarius, Pclteney (not Linn.), Hutchins, Hist. Dorset, p. 44. — 



Blainv. Faune Franc,. Moll. p. 277, pi. 11, f. 10. 

 „ umbilicatus, Mont. Test. Brit. p. 286. — Maton and Rack. Trans. 

 Linn. Soc. vol. viii. p. 153. — Turt. Conch. Diction, 

 p. 186. — Fleming, Brit. Animals, p. 322. — Forbes, 

 Malac. Monens. p. 24, animal. — Macgill. Moll. Aberd. 

 p. 324. — Brit. Marine Conch, p. 160. — Brown, Blast. 

 Conch. G. B. p. 18, pi. 11, f. 9, 11.— Wood, Ind. Testae, 

 pi. 29, f. 48. — Hanley, Young Conch, p. 70. 

 „ obliquatus, DlLLW. Recent Shells, vol. ii. p. 779. 



