W. S. Sudleston — On the Yorkshire Oolites. 301 



Description. — Specimen from the Dogger (zone 1), Peak (Blue 

 Wyke). York Museum. 



Length , 18 millimetres. 



Width 21 „ 



The shell-substance has been partly eaten away, the columella 

 having entirely perished. Hence the appearances of the front 

 aspect of the shell (Fig. 11a) must be taken for no more than they 

 are worth. The apical view discloses a very short spire composed 

 of about three tumid whorls, largely hollowed at the suture, and 

 developing rapidly into a large body-whorl, which shows a slight 

 flatting posteriorly, but is otherwise tumid and rounded throughout. 

 The ornaments consist of spiral lines of varying strength, somewhat 

 irregularly spaced. About a dozen, stronger than the rest, may be 

 counted on the body- whorl. There 'does not seem to be any trans- 

 verse ribbing, but a certain kind of reticulation is produced by 

 occasional thickening due to periodical arrestation of growth, and 

 also by fine transverse strife. Other indications are wanting. 



Belations and Distribution. — From Normandy specimens of Neri- 

 topsis Bajocensis, the Dogger fossil, is distinguished by the absence 

 of the transverse undulations on the posterior region, whilst from 

 Neritopsis Pkilea it is distinguished by the absence of the trans- 

 verse tuberculated lines. In the Inferior Oolite of Bradford Abbas 

 a Neritopsis occurs very similar to this one, but with a perfectly 

 flat posterior area, such as appears never to have existed in the 

 Dogger specimen. Hence both in Yorkshire, in Dorset-Somerset, in 

 Normandy, and in the East of France fossils occur, in or about the 

 same horizon, which present a general similarity, but with differences 

 of detail. The Bradford Abbas fossil is so well preserved as to 

 warrant its being described as a distinct variety. No specimens 

 from the Yorkshire Dogger are quite good enough for this. It is 

 extremely rare, and is one of the species which altogether escaped 

 the notice of Phillips. 



No variety of Neritopsis Bajocensis seems to have been noted in the 

 Inferior Oolite of any other part of England, until we reach Somer- 

 setshire. Mr. Tawney recorded three specimens from Dundry, and 

 no doubt many more have been added since then to the Collection at 

 the Bristol Museum. Brauns does not record Neritopsis from the 

 Middle {i.e. Brown) Jura of N.W. Germany, but Laube (Gast. des 

 braunen Jura von Balin, p. 6, pi. i. fig. 9) figures a rather typical 

 form of N. Bajocensis. 



65. — Neritopsis canaliculata, D'Archiac, 1843. PI. IX. 

 Figs. 12a, 126. 



1843. Turbo canaliculatus, D'Archiac. Mem. Soc. Geol. de France, 5, p. 379, 



pi. 29, fig. 6. 

 1849. Turbo Archiaci, D'Drbigny. Prod. i. p. 300 (Bathonieu). 

 1852. Turbo Archiacii, D'Orbigny. Terr. Jurass. ii. p. 351, pi. 334, figs. 8—10. 

 1863. Neritopsis Archiaci, D'Arch. species, Lycett, Suppl. p. 21, pi. 31, figs. 7, la. 



Bibliography, etc. — Not quite comprehending why D'Archiac's 

 specific name should be suppressed, and believing that no other 



