44 MOLLUSCA FROM THE CRAG. 



Shells with an elongated canal, which properly constitute the genus Fusus, are 

 characteristic of a tropical climate. The greater part of the species of this genus from 

 the Crag are northern forms. 



1. Trophon antiquum. Miill. Tab. V, fig. 1, a — k. 



Tritonium antiquum. Miill. Zool. Dan. tab. 118, fig. 1-3, 1/73. 

 MuREX coNTRAEius. Gmel. Syst. p. 3564, 1/88. 

 Fusus ANTiauus. Ency. Meth. pi. 426, fig. 5. 



DESPECTUS (?). - pi. 426, fig. 4. 



— coNTRARius - pi. 437, fig. 1, a 6. 

 MuREX DESPECTUS. Moiit. Test. Brit. p. 256, 1803. 



ANTIQUUS(?). - - - p. 257. 



— STBiATUs. J. Sow. Min. Conch, t. 119, 1815. 



— «ar. CARINATUS. - - - t. 22, 1813. 



— CONTRARIUS. - - - t. 23. 



BucciNUM CONTRARIUM. G. Sow. Genera, fig. 4. 



FusDS CONTRARIUS. Phil. En. Moll. Sic. vol. ii, p. 179, 1S44. 



— — Nyst. Coq. foss. de Belg. p. 500, pi. 41, fig. 1. 



— ANTiauus. Latn. An. sans Vert. (2d edit.) ix, p. 477, 1845. 



CARINATUS - p. 449. 



— CONTRARIUS ------ p. 462. 



SINISTRORSUS (?). p. 374. 



Tritonium antiquum. Loven. Ind. MoU. Scand. p. 11, 1846. 



Bale. Hist, of Harwich, pi. 10, fig. 5-6, 1730. 



Tr. Testa crassd, turritd, fusiformi, sulcata, carinatd, vel tenuissime striata ; apice 

 papilliformi, anfradibus valde convexis, tumidis ; aperturd ovatd ; labro simplici, intus 

 lavigato ; canali brevi, emarginatd. 



Shell variable, strong, thick, ponderous, fusiform, turreted, sulcated, bicarinated, 

 or finely striated, with a white, naked, and mammillated apex ; whorls convex, tumid ; 

 aperture ovate ; lip simple, smooth within ; canal short. 



Axis, 6 inches. 



Locality. Red Crag, jjassim. 



Mam. Crag, Bramerton and Bridlington. Recent, Britain. 



I have very little doubt of the shell found so abundantly in the Red Crag, with its 

 sinistral volutions, being a variety of the common Tr. antiquum. This species is exceed- 

 ingly variable, and no dependence can be placed upon any proportional dimensions of its 

 aperture, as may be seen from the c.Ktremes of variation figured in Tab. v, and between 

 which every intermediate form may be procured. Some specimens have an aperture 

 exceeding two thirds of the axis, while in others it is not more than one third. The 

 smooth and obtuse state of the young shell, at the apex of perfect specimens, is a good 

 distinguishing character in this species ; but in the greater number of the fossil speci- 

 mens that part is destroyed, excepting in the striated variety, so common at Walton- 

 on-the-Naze. The Belgian shell, figured by M. Nyst, is an extreme variety of this 

 species. I have never seen the canal so much produced in the English specimens ; 



