W. H. Hudleston — On the Yorkshire Oolites. 247 



54. — -Ambekleya (Turbo) clavata. Bean MS. Plate VIII. Fig. 8. 



Description. — Specimens from the Oxford Clay (Zone 6), Scar- 

 borougli. Bean Collection, British Museum. 



None of the shell-substance is retained, but we seem to have 

 a tolerably faithful outline of the exterior and ornaments. For a 

 fossil in the O.C. the shape is well maintained, though not sufficiently 

 to attempt any measurements. The specimen was probably upwards 

 of 50 millimetres in length. The aperture is not really preserved, 

 the appearance of one shown in the figure merely representing the 

 fancy of .the person . who originally developed the fossil, subse- 

 quently rendered with almost grotesque fidelity by the artist. 



Shell eucycloid, turbinated ; whorls tumid, yet angular, with a 

 wide sutural hollow. The penult probably had 4 nodular spiral 

 bands, the central pair constituting the double keel. In the body- 

 whorl the uppermost spiral is close to the suture, the granulations 

 being wide apart and spinous ; the second spiral is a somewhat faint 

 line, slightly nodular at wide intervals : the third and fourth spirals 

 constitute the double keel, the tuberculations on the upper of these 

 (3) are wider apart than on the lower one (4), which is slightly the 

 more salient ; the fifth spiral has close tuberculations resembling 

 those of the fourth. Of the actual base of the shell only a portion 

 remains. It is rounded and spirally lineated at wide intervals by 

 lines alternately sharper and fainter, which are slightly nodulous. 

 Traces of the fine radial or axial ornament are faint throughout the 

 specimen. 



Belations and Distrihution. — The appearance of such a fine Gas- 

 teropod as this in the Oxford Clay of Scarborough is so wholly 

 nnexpected that, apart from the dilficulties connected with imperfect 

 preservation, one hardl}^ knows what to make of the phenomenon. 

 It evidently belongs to the group to which Turbo ornatus, Sow., 

 Turbo capitaneus, Miinst., and Turbo spinulosus, Miinst., belong. 

 These were all regarded by Mr. Tawney (Dundry Gasteropoda, p. 19) 

 as specifically the same. The real facts of the case are that a number 

 of forms occur where the group is at all plentiful, as is the case in 

 the I. 0. of Bradford Abbas. For instance, the very handsome and 

 characteristic specimen figured by Mr. Tawney {op. cit. pi. i. fig. 9) 

 bears no very special resemblance to Sowerby's type figure, though 

 it represents the prevailing form at Bradford Abbas. If there was 

 more certainty, I would not hesitate to call the fossil now under 

 consideration Amberleya ornata, var. clavata. There are, however, 

 very considerable differences in the ornamentation of Bean's shell, 

 as compared with that of the prevailing representative of the ornata 

 group in the Inferior Oolite of the far south-west. 



Both this species and Amberleya armigera represent the ornata- 

 group in their respective horizons ; but whilst the latter is fairly 

 plentiful in the Cornbrash, only one other specimen of A. clavata is 

 known to me from the O.C. of Yorkshire. That also was Bean's 

 specimenj and is now in the York Museum. 



