W. H. Hudleston — On the Yorkshire Oolites. 125 



the projection of the posterior border of each succeeding whorl. 

 In smaller specimens the spiral angle is rather wider : hence there 

 is very little difference in this respect between T. Scarhurgensis, and 

 small specimens of T. strigosus. 



There is a tablet in the Leckenby Collection which contains half a 

 dozen specimens referred to T. strigosus, and a few may be seen in 

 other collections. Hitherto only found in the Cornbrash of Gris- 

 thorpe.^ 



77. — Teochus stjbglaber, sp. n. Plate HI. Figs. 6, Qa. 

 But compare — 



Trochus glaber, Koch and Dunker, Verstein. p. 24, pi. i. fig. 12, from the Lias. 

 Trochns Dunkeri, Morr. and Lye, Gt. OoL Moll. p. 61, pi. x. fig. 3. 



Description. — Specimen from the Cornbrash (zone 4), Scarborough. 

 Leckenby Collection. 



Height 13 millimetres. 



Width 10 ,, 



Spiral angle 52°. 



Eatio of body-whorl 40 : 100. 



Shell small, conical, (?) imperforate ; spire consists of 6 or 7 

 whorls increasing pretty regularly under an angle of 52° ; suture 

 close, but very distinct. Anterior area of each whorl slightly tumid, 

 posterior area slightly constricted ; the effect of this is to cause each 

 whorl slightly to overhang the succeeding one. 



The ornaments consist of fine spiral strige, very numerous and 

 somewhat closer together in tbe anterior than in the posterior region ; 

 .these striae are decussated by backward sloping transverse strise, 

 which scarcely reach the anterior margin. Base flat ; other indications 

 wanting. 



Relations and Distribution. — It is quite possible that this very 

 elegant little shell approaches T. Dunlceri, said by the authors of the 

 Great Oolite MoUusca to be tolerably abundant in the White Stone 

 of Eastcombs and Bussage. It differs in possessing more whorls, 

 and also in having a fine system of ornamentation which has been 

 well preserved in the waxlike calcite of the Yorkshire Cornbrash. 

 This might not be equally well preserved in another matrix. As 

 regards T. glaber, K. and D., there is probably a still wider margin 

 of difference : it should also be mentioned that Eugene Deslongchamps, 

 in 1860, expressed his opinion that Koch and Bunker's species was 

 a Pyramidellid belonging to the genus Niso. 



Trochus subglaber is confined, as far as I know at present, to the 



1 On looking over the Bean Collection at the British Museum, I found a specimen 

 of Trochus in an indurated gritty marl of a grey colour, which might be either 

 Cornbrash or Kelloway Rock — most probably the latter. This fossil is evidently 

 allied to the group just described (see Llate III. Fig. 5). 



The spiral angle is about 65°-70°. There is no projection of the basal belt; on 

 the contrary, the sudden increase is just below the suture, as in T. Scaybiirgensis. In 

 the body-whorl the spaces between the spirals are remarkably wide, and besides the 

 usual oblique axial striation, fine spiral lines may be noted between the more prominent 

 spirals. A similar feature may be noted in a Trochus belonging to the Yorkshire 

 Philosophical Society, which is either from the Cornbrash or Kelloway Rock. Shall 

 we give these a temporary distinction as T. Scarhurgensis, var. mterlincatus ? 



