128 MOLLUSCA FROM THE CRAG. 



Avis, J of an inch ; diameter, |. 



Locality. Red Crag, Sutton. 



This species is at present rare in my cabinet. It appears to differ from T. mille- 

 granm, the species to wliich it approaches nearest, in having the ridges granulated ; 

 but it is without the imbricated character of that species, and the edges of the volutions 

 are not so sharp and angular as in that shell, or in T. miliaris ; the volutions, also, are 

 not so flat. It differs from any of the specimens of T. exiguus that I have seen, in 

 having the outer edge of the volutions less angulated, and in wanting the distinct basal 

 ridge of that shell, and moreover its sides are less flat. Our shell has two or some- 

 times three prominent granular ridges at the lower part of the volution. It is more 

 finely and regularly granulated than the young of T. subexcavatus, for which it might 

 otherwise be mistaken. 



Sect. b. UMBILICATED. 



9. Trochus villicus (?). Phil. Tab. XIV, fig. 4, a—b. 



Trochus villicus. Phil. En. Moll. Sic. vol. ii, p. 152, t. 25, fig. 14, 1844. 



Tr. Testa conicd, obtusiuscidd, crassd; anfradibus quingue, planulatis, superne sub- 

 angulatis ; transversim dngulatis, cingidis 5 — 7, incBqualibus ; anfractu ultimo angulato ; 

 columelld obsolete unidentatd ; umbilico parvo. 



Shell conical, somewhat obtuse, thick, and strong, vnth about five volutions, rather 

 flat, and projecting slightly at the upper part, ornamented with 5 — 7 unequal ridges, 

 imbricated by the elevated and reflected lines of growth ; base of volution angulated 

 and striated ; columella with an obsolete tooth ; umbilicus very small. 



Awis, \ of an inch. 



Locality. Cor. Crag, Sutton. 



Red Crag, Sutton. Recent, Mediterranean. 



I have about half a dozen specimens of this shell in my cabinet from the Red Crag, 

 which appear to resemble what M. Philippi has considered a new species ; and in his 

 examination of the recent shell he may have detected more decided characters for its 

 establishment; but, judging from my fossils alone, I consider it only a variety of 

 T. Adansoni. My specimens have but a very small umbilicus, which may arise from the 

 position of the volutions being a little more erect ; in other respects it corresponds so 

 closely with his figure and description that it may be considered the same. From five 

 to seven large and obtuse irregular-sized ridges cover the upper side of the volution, 

 and there are about the same number on the base, but rather smaller and more 

 regular; the ridges are all crossed by erect and slightly reflected lines of growth, 

 which are most distinct between the ridges. 



