GASTEROPODA. 133 



is nothing in our shell hke the holes represented in the enlarged portion of his figure ; 

 I have therefore left it for the present with the name given to it in my Catalogue, until 

 it can be correctly determined by a comparison with the Mediterranean specimens. 



17. Trochus obconicus. S. Wood. Tab. XIV, fig. 10, a — d. 



Trochus obconicus. S. Wood. Catalogue 1842. 



Tr. Testa pusilld, orbiculato-conoided, perforata ; apice obtuso ; anfractibus quatuor, 

 superne planulatis, subttis convexis ; transversivi lineatis, lineis elevatis, cremdatis ; mturk 

 profundis, subcanaliculatis ; umbilico parvo. 



Shell small, obconical ; apex rather obtuse ; whorls somewhat flat above, convex 

 beneath, with transverse crenulated lines or striae ; suture deep, subcanaliculated ; 

 aperture obtusely quadrate, and a small umbilicus. 



Axis, i of an inch. 



Locality. Cor. Crag, Sutton. 



This is an abundant shell, and my specimens are all from one locality. In general 

 the transverse lines are regular in distance, and are about eight in number, crossed 

 by elevated and imbricated lines of growth, which give the exterior a crenulated 

 appearance ; the lines being prominent, particularly the upper and lower ones, produce 

 an apparent canal at the suture. In some specimens there are only four elevated lines, 

 var. /3, fig. a — b. The base is convex, with about eight spiral lines ; there is a small 

 umbihcus, and the shell is nacreous. It is possible this may be Tr. crispulus, Phil., but 

 ray specimens have not the rounded volutions of that shell as represented in his figure, 

 (t. 25, f. 12.) 



18. Trochus ditropis. S. Wood. Tab. XIV, fig. 9, a—b. 



Teochus bicaeiniferus. S. Wood. Catalogue Itj42. 



Tr. Testa minutd, orbiculato-conicd, perforatd ; sjnrd depressd ; anfractibus 3 — 4, 

 rotundatis, bicariniferis ; transversim striatis, et tenuissime imbricatis; aperturd orbiculuto- 

 quadratd ; umbilico parvo profunda . 



Shell small, orbiculato-conical, striated along the volutions, and very finely imbri- 

 cated across them ; whorls round, convex beneath, with two sharp and prominent 

 keels ; aperture subquadrate ; umbilicus rather small, and deep. 



Axis, ^ of an inch. 



Locality. Cor. Crag, Sutton. 



This pretty little shell is not very abundant, and I have as yet seen it but from one 

 locality. The volution bears two elevated and sharp carinae, di\'iding it into three 

 unequal parts ; the spaces above and beneath being wider than that between the keels ; 

 but, as the volution joins the lower keel, one carina only is visible upon the spire. 

 The transverse or spiral striae are broad and flat ; about half a dozen are on the upper 



