50 W. E. Eudleston—The Yorkshire Oolite. 



observe that their species is near to N. Moreauana, D'Orb., and 



N. Gottaldina, D'Orb., from the Coral Rag. 



Description. — Specimen from the Coral Eag — probably of Seamer 



or Ay ton (Strickland Collection). Figs. 3a, &, x 1-|. 



Length 16-5 millimetres. 



Width 18-7 



Length of last whorl 13- ,, 



Shell transversely ovate oblong. Spire short, formed of about 

 three whorls, of which the last is immense in comparison with the 

 rest of the spire. The whorls are widely separated : the body- 

 whorl is flatted posteriorly, so that the shell is tumid angular rather 

 than convex. The ornaments consist of a series of moderately 

 strong transverse ribs, of which three or four towards the centre 

 are somewhat more prominent : the longitudinal ribbing is less 

 strongly indicated. The nodes at the intersections were probably 

 spiny, and the whole pattern is coarse and irregular. 



The aperture is wide and circular, with a thick peristome, the 

 edge of which is crenulated, except upon the inside, where the lip is 

 smooth and prominent.^ 



Another specimen (Leckenby Collection), Fig. 3c, natural size. 



Length 22 millimetres. 



Width 25 



Length of last whorl 18 ,, 



This is a much larger specimen than the one previously described, 

 but the proportions are nearly the same. The shell has suffered 

 from wear, but enough character remains in the angular outline of 

 the upper part of the body-whorl, and the irregularity of the 

 transverse ribbing, to warrant the identification. 



Relations and Distribution. — This somewhat average form is doubt- 

 less related to the two species next described, though it clearly 

 differs from either, both in contour and character of ornament. 

 Perhaps the nearest Corallian form described from the French beds 

 is N. Gottaldina, D'Orb. (Terr. Jurass. vol. ii. p. 227, pi. 301, figs. 

 11 — 13), but that species is smaller. 



N. Guerrei, as identified, occurs principally in the Coral Eag of the 

 Scarborough district (Seamer, Ay ton, Brompton), where Oxfordian 

 forms would seem to have lingered more than on the south side of 

 the Vale of Pickering. It has been quoted from Upware possibly 

 in mistake for N. decussata, and is mentioned by Whiteaves in the 

 Oxford list. 



1 As one of the characteristic features of Neritopsis is held to be the notch at 

 the columellar lip, it might be objected that, in the case of this specimen, no such 

 notch is shown. A similar objection maybe urged in the case of all D'Orbigny's 

 figures in the Terrains Jui-assiques. Two reasons may be adduced for this. Firstly, 

 the columellar notch may not have been so strong in the Secondary as in the Tertiary 

 species. Secondly, it is quite certain that the presence of a hard matrix tends to 

 obscure what should be the characteristic feature, and more complete development, 

 where safe, might reveal the existence of the notch. In the very well preserved 

 Tesson Collection, now in the New Natural History Museum, there is only one 

 specimen of Neritopsis where the notch is visible. In this case the anterior portions 

 of the inner lip are decayed away, but, as the aperture happens to be quite clear of 

 matrix, we are able to see the entire cavity. 



