W. IT. Hudleston — On the Yorkshire Oolites. 297 



a slight flattening of the posterior area may be noted ; the rest of 

 the whorl is uniformly tumid, and entirely plain, with the exception 

 of fine lines of growth. There are also certain coarse markings 

 (not shown in the figure) which probably indicate stages of increase. 



The aperture is large in every direction ; the outer lip is crescent- 

 shaped and produced, the substance being rather thin, although the 

 adherence of matrix on the inside seems to show the contrary. The 

 inner lip is straight, with a wide callus on the flattened columella. 

 It is not certain whether there were any denticulations on the edge 

 of the pillar-lip, since this part of the specimen is somewhat worn ; 

 there are indications which might be thus interpreted. 



Another specimen. — Same horizon and locality. Leckenby Col- 

 lection. Figs. 5a, 5b. 



Heiglit 9 millimetres. 



Eepresents a smaller shell, and one where the apex is rather less 

 conspicuous, or else in a worse state of preservation than the pre- 

 ceding. The body- whorl is well preserved in a fine black spathic 

 material, and shows extremely delicate lines of growth, but none of 

 the rugosities of the larger and older specimen. 



Another specimen. — Same horizon and locality. York Museum. 

 Phillips's Type refigured. Fig. 6. 



Height about 1 1 millimetres. 



The apical portion of the spire is not well preserved, but in the 

 body-whorl may be noted the characters previously described. The 

 aperture is very fairly preserved, though there can be no doubt that 

 a portion of the outer lip has been broken, away. Phillips's figure 

 (op. cit. pi. xi. fig. 25) is enlarged about 1^ times, and is a remarkably 

 faithful representation of the shell. The wide semicircular sweep 

 of the outer lip is there well given, as also the straight pillar-lip 

 with the wide callus on the flattened columella area — all in complete 

 contrast to the Naticas of the Dogger, as may be seen on referring 

 to the first plate of the present Memoir (Geol. Mag. 1882, PI. V.). 



Relations and Distribution. — In the Yorkshire Dogger this smooth 

 Nerite is perhaps larger and probably more numerous than on the 

 same horizon further south. Nevertheless it should be borne in 

 mind that here also its size varies wonderfully, the specimen, 

 figure 4, being exceptionally large. Still the average is probably 

 three times the size of Sowerby's type. Being fairly abundant in 

 the Yorkshire Dogger, one would expect to find this species low 

 down in the Inferior Oolite of other districts. Can the Natica 

 neritoidea, quoted as common in the Northampton Sand (Judd, 

 Geology of Rutland), represent it? A species of Nerita is quoted 

 by Mr. Walford from the Inferior Oolite of Hook Norton 

 (Q.J.G.S. 1883, p. 240). Dr. Wright quotes "Natica" tumidida, 

 Phil., as one of the fossils of the Oolite Marl of Cheltenham 

 (Q.J.G.S. vol. xvi. p. 13), whilst from the Pea Grit (p. 11) he 

 quotes Nerita minuta, Sow. Perhaps the difference is only one of 

 size. No Nerite is quoted by Mr. Tawney from Dundry, nor any- 

 thing that could in any way be taken to represent Nerita minuta. 



