52 W. R. EurUedon—The Yorkshire Oolite. 



Description. — Specimen from the Coral Eag of North Grimston 

 (Strickland Collection). 



Total length 12-5 millimetres. 



Width 14-25 



Length of last whorl 11 "0 „ 



Shell transversely oval oblong. Spire extremely short, and formed 

 of two to three whorls, of which the last is immensely larger 

 every way than the others. Body-whorl flattish posteriorly^, afford- 

 ing an angular rather than a convex outline. Ornaments strongly 

 sculptured and of great regularity. About twelve stout transverse 

 ribs are met at right angles by a system of longitudinal ribbing 

 somewhat less prominent. The points of intersection are marked 

 by thick tuberculations, the intervening meshes being regular 

 oblongs of considerable depth. 



The anterior portion of the body- whorl and the aperture are too 

 much concealed in matrix for accurate description. 



Belations and Distribution. — The points of resemblance in this 

 well-marked species to the two previously described are, in a great 

 measure, those common to the genus. The contour and ornamenta- 

 tion separate it clearly from N. Moreauana, and although it has 

 stronger affinities with the form referred to N. Guerrei, yet the 

 regularity and nearly uniform strength of the ribbing is a good 

 character which may be relied upon in instituting a comparison with 

 that species. 



N. decussata is very rare in Yorkshire, not more than two 

 specimens at the utmost having come under my notice. A larger 

 variety, w hich may probably be referred to this species, occurs in 

 the Coral Eag of Upware, which has so many fossils in common 

 with the North Grimston Eag. The same species has also been 

 found in the Coral Eag of Wiltshire. Buvignier states that JV. 

 corallensis (believed to be a synonym) is rare in the Corallian of 

 the Meuse. 



No species of Neritopsis in any way resembling either of the 

 three described is quoted from this horizon in North Germany. Nor 

 have any of them been noticed at Boulogne or at Weymouth. A 

 large development of actual Coral seems to have been favourable to 

 this section of the genus. 



Genus Turbo, Linnseus, 1758. 

 This ffenus was the exhaustive division in which numbers of 

 Jurassic shells were put as a sort of temporary restmg-place. 

 After the removal of the section of Littorina previously described, 

 the species remaining are neither numerous nor important as con- 

 tributing to swell the shell-beds of the Corallian rocks in York- 

 shire. Under this general heading we may for present purposes 

 include Crossostoma, Lycett, 1850, Monodonta, Lamarck, 1801, and 

 DelpMnula, Lamarck. 



39. — Turbo (Crossostoma) corallensis, Buvignier, 1852. 



Plate III. Figs. 4a, 6. 



Turho corallensis, Buvignier, 1852. Stat. geol. de la Meuse, p. 37, pi. 24, figs. 21, 22. 



