GASTEROPODA. 125 



it a greater diameter. Specimens from the Red Crag appear to be very rare ; 

 fig. 9 h is one that approaches nearer our common form; fig. 9/, ^is from the 

 Coralline Crag, and appears to resemble Tr. co?udoides, Lamarck. Trochus Icevigatus, 

 Sow., is probably only a specimen of this species, similar to fig. 9 c, which I 

 imagine is an abraded individual from the Red Crag, upon which there is not the 

 slightest vestige of strias, the outer coating having been entirely removed ; its only 

 markings are the lines of growth ; fig. 4 is also presumed to be a monstrous and 

 decorticated specimen of this species. 



3. Trochus conulus. Linn. Tab. XIII, fig. 5, a — b. 



Trochus conulus. Linn. Gmel. p. 3579. 



— Lam. 2d edit. Hist. Nat. des An. sans Vert. t. 9, p. 142, 1835. 



— Phil. var. a. En. Moll. Sic. vol. i, p. 175, 1836. 



— Thorpe. Brit. Mar. Conch, p. 255, 1844. 



— S. Wood. Catalogue 1842. 



Tr. Testa conicd, nitidd, laevigata ; apice acuto, granidato ; anfractibus plants, ad basim 

 angulatis ; itiferne cingulo, crassiusculo marginatis, infimd facie planatd ; aperturd tetragond. 



Shell, conical, smooth, and naked, with an acute and granulated apex ; sides flat, 

 and a distinct ridge at the carinated edge of the volution ; base nearly flat ; colu- 

 mella suboblique ; aperture trapeziform. 



Altitude, 1 inch ; diameter, -|. 



Localitg. Cor. Crag, Ramsholt. Recent, Mediterranean and Britain. 



But two or three specimens of this species have come into my possession, which 

 appear to correspond with the smooth glossy form of what has hitherto been called 

 T. conulus. It is very possible this may be a variety of T. ziziphinus. 



Prof. Forbes and Mr. Hanley are of opinion that T. conulus is specifically distinct 

 from T. ziziphinus, and as those gentlemen are better acquainted with the recent 

 species than myself, I have given it upon their authority. 



4. Trochus formosus. Forbes. Tab. XIII, fig. 2, a — b. 



Trochus formosus. Forbes. An. and Mag. Nat. Hist. 1847, vol. xix, p. 96, pi. 9, fig. 1. 

 — quadricinctus. S. Wood. Catalogue 1842. 



Tr. Testa conicd, imperforatd, granulatd ; anfractibus quinque, planiusculis ; cingulis 

 quatuor, elevatis instructis ; ultimo anfractu ad basim subangulato ; aperturd tetragond. 



Shell regularly conical, with flat sides, and slightly elevated spire ; volutions five, 

 ornamented with about four elevated and granulated ridges ; base rather flat ; edge 

 of volution subangulated, with a subquadrate or trapeziform aperture. 



Axis, \ an inch. 



Localitg. Cor. Crag, Sutton. 



Red Crag, Sutton. Recent, British Seas. 



I have but a few specimens of this from either formation, and Prof. Forbes con- 

 siders them identical with his recent British species. As the name given in my 



