300 W. H. EucUeston—On the Yorkshire Oolites. 



and Lycett's figure (pi. xv. fig, 3). The only Dogger specimen 

 ever seen by me is in the Lycett Collection at Jermyn Street ; in 

 this one the ribbing is bolder and shows an approach to Nerita 

 pseudo-costata. 



Thus Nerita costiilata, Deshayes (N. costata, Sow.), occurs, though 

 very rarely, in all three zones of the Inferior Oolite in Yorkshire, 

 whilst N. pseiido-eostata is confined to the Dogger. It is also quoted 

 as rare in the Northampton Sand (Judd, Geology of Eutland, p. 282), 

 and we have seen that it occurs occasionally in the Inferior Oolite of 

 the Cotteswolds, but has not yet been noted in England further 

 south than Ancliff. 



Subgenus Nekitopsis, Grateloup, 1832. 



With reference to Neritopsis, see "Corallian Gasteropoda," in 

 the Geological Magazine for the year 1881, p. 49, D'Orbigny 

 (Terrains Jurassiques, ii. p. 221) says that the shell is analogous to 

 that of the Nerites ; but, judging partly from his description and 

 partly from his figures, we arrive at the conclusion that the Jurassic 

 representatives of Neritopsis present considerable differences as 

 regards the inner lip to the ordinary Nerite. Instead of the large 

 flattened columellar area covered with callus, and in most cases 

 denticulated on its very straight margin, the inner lip is hollowed 

 out, and D'Orbigny says is without teeth. Yorkshire specimens of 

 Neritopsis are seldom sufficiently well preserved to make us feel sure 

 on this latter point, but we may fairly accept D'Orbigny's statement, 

 since he had the handling of so many excellent specimens. The 

 Jurassic species are also for the most jjart characterized by spiral 

 ornamentation, with more or less transverse decussation. 



These beautiful fossils, rare enough in the Corallian beds, are still 

 rarer and worse preserved in our Oxfordian and Lower Oolites. 

 None are quoted from the Yorkshire Lias. . . 



64, — Nekitopsis Bajocensis, D'Orbigny, 1849. Dogger Variety. 

 Plate IX. Figs 11a, h, c. 



1849. Neritopsis Bajocensis, D'Orb. Prod. i. p. 264. 



1852. „ ,, „ Ter. Jurass. p. 223, pi. 300, figs. 8-10. 



Compare also 



Neritopsis Fhilea, D'Orbigny, Terr. Jurass. p. 222, pi. 300, figs. 5-7 (Et 

 Toarcien) . 



Bibliography, etc. — We obtain most of our information regarding 

 the Jurassic species of Neritopsis from the pages and exquisite plates 

 of the Paleontologie Franc;aise. The earliest ^species recorded is 

 N. Eebertana, from the Middle Lias of Fontaine-Etoupe-Four. This 

 is a smallish and very rugose species, whose exact counterpart 

 occurs in the Dorset-Somerset district, and most probably on, or near, 

 the same horizon. Next come two species which greatly resemble 

 each other — Neritopsis PJiilea is quoted from the Toarcian of the 

 environs of Semur (Cote d'Or), and N. Bajocensis from the I.O. 

 of Moutiers (Calvados). The Yorkshire specimen does not exactly 

 agree with either, but seems to be an intermediate form. 



