198 W. IT. Sudleston — On the Yorkshire Oolites. 



to a rock in North Oxfordshire, wlience magnificent shells of N. 

 " Lechhamptonensis " have been obtained lately. 



Description. — Specimen from the Inferior Oolite limestone of the 

 Castle Howard district (zone 2). Collection of the Leeds Philo- 

 sophical Society. 



Type Specimen Eefigured. 



Length (restored) 104 mm. 



Width , 95 ,, 



Eatio of hody-whorl to entire shell 79 : 100. 



Spiral angle, about 120°. 



Shell subangular, nearly as wide as long, spire moderately elevated. 

 Whorls probably 4-5, increasing in regular proportion with great 

 rapidity, so as to produce an enormous expansion of the body-whorl. 

 All the whorls are distinguished posteriorly by a sloping tabulate 

 surface, which rises slightly to meet the strong keel at the angle of 

 the whorl. The keel, which in the body-whorl obtains immense 

 proportions, imparts an angular character to all the whorls, which 

 otherwise are convex, almost tumid, and devoid of regular ornament, 

 except the rugose lines marking the stages of growth. There is, 

 however, towards the middle of the body-whorl, a spiral band, 

 developed in this specimen by weathering, which indicates a 

 peculiarity less strongly marked in specimens from other districts, 

 but which in the case of this particular shell has served to fix the 

 name. 



The shell substance of the body-whorl, now consisting entirely of 

 spar, has a thickness of 5 mm. The angular outline is not repre- 

 sented in the cast (see right-hand upper corner of Fig. 4), which is 

 rounded as in the well-known casts of N. Lechhamptonensis. The 

 aperture is extremely wide. There is hardly any umbilicus, the 

 shell substance being 20 mm. thick in this region. When this is 

 dissolved awaj^ the corresponding space in the cast is very wide, 

 so that the connexion between the almost corkscrew-like form at 

 Denton and this shell is not so obvious at first sight. It serves to 

 show the danger of describing a fossil from a cast. 



Another specimen from the Dogger (zone 1), Bean Coll. B. M. 

 (Plate V. Fig. 5.) 



Length 23 millimetres. 



Width 22-5 „ 



Ratio of body-whorl to entire shell 72 : 100. 



Spii-al angle 128''. 



The dimensions are very different, but the proportions and general 

 shape are sufficiently near to induce me to regard this as in all 

 probability a small specimen of N. cincta. 



Relations and Distribution. — It must be borne in mind that the type 

 specimen is, as regards Yorkshire, unique both in size and condition. 

 Specimens are very scarce, and none have, as far as I know, been 

 procured from the Mount Pleasant Quarry, the principal locality 

 for Inferior Oolite fossils. Whether we regard the fact from a 

 stratigraphical or a palseontological point of view, the appearance of 

 this singular and enormous shell, on the same horizon throughout 

 England, north of the Avon, is almost a portent. There are many 



