58 W. H. Hudleston — The Yorkshire Oolite. 



equally fine lines of growth. No umbilicus : aperture involved in 

 ma rix. 



Eelations and DisUihition. — In ornamentation this very pretty 

 species approaches Trochus ecJiinatulus, Buvig. (op. cit. p. 38, pi. 26, 

 figs. 7 and 8), from the Upper Coral Rag of Dun, but Buvignier's 

 is a more elongated form. The Yorkshire specimen is unique at 

 present. 



47. — Tkochus Aytonensis, Blake and Hudleston, 1877. Plate III. 



Fig. 12. 

 Trochus Aytonensis, Blake and Hudleston, 1877, Quart. Joiirn. Geol. Soc. vol. xxiii. 

 p. 365, pi. xiv. fig. Id. 



Description. — Specimen from the small shell -bed in the base of the 

 Coralline Oolite at Pickering (Leckenby Collection). 



Lena^th 6 millimetres. 



Width 5-5 „ 



Spiral angle 60''. 



Shell conical, trochiform, not umbilicated. Spire composed of 

 whorls vi^hich are flat, increase with great regularity, and are 

 scarcely separated by the suture. Each whorl is ornamented with 

 a nodular band at the base, and three rows of tubercles above. 

 These tubercles are large, well cut, and drawn out transversely, so 

 that each tubercle is oval rather than circular. The band at the 

 base of the body-whorl forms a conspicuous prominence, and is worn 

 nearly smooth. Base nearly flat ; no ornaments visible. 



Eelations and Distribution. — From the previously described species 

 the difference in the ornamentation clearly separates it. T. Ayton- 

 ensis has affinities with T. eehinatulus, Buv., and also with T. cari- 

 neJlaris, Buv. {op. cit. p. 39, pi. 27, figs. 10 and 11). The type 

 specimen, described by Blake and Hudleston, is from the Coral Eag 

 of Ayton. Only three specimens are known at present. 



48.— Tkochus, sp. Plate III. Fig. 13. 

 Description. — Specimen from the Coral Eag of Brompton (my 

 Collection). 



Length 7 millimetres. 



Width 7-5 ,, 



Spiral angle 70°. 



Shell conical, trochiform, nearly equilateral, slightly wider than 

 high. The spire is composed of few whorls, which are nearly flat, 

 and ornamented by three rows of granulated costse, the anterior row 

 being slightly bicarinated, so as to make a sort of fourth row. Base 

 flat ; aperture subquadrate. 



The specimen has suffered to a certain extent from exposui'e, so 

 that the character of the ornaments is somewhat indistinct. Enough 

 however remains to show that it cannot be referred to any of the 

 species previously described. 



EXPLANATION OF PLATE III. 



Fig. 1. Neritopsis decussata, Miinster. Coral Eag of North Grimston. 



Strickland Collection. x Ij. 

 ,, 2a «& b. Neritopsis Moreauana, D'Orbigny. Coral Rag of Brompton. 

 Strickland Collection. Back and front, x 1^. 



