W. S. HucUeston—On the Yorkshire Oolites. 299 



Shell small, transversely ovate, not nmbilicated. Spire low, but 

 not exactly depressed, yielding a spiral angle of about 150°. Tlie 

 flanks of all the whorls are ornamented with very strong transverse 

 (longitudinal or axial) costse, regular and sepai'ated by sulci, about 

 twice the width of each rib. Aperture wide, the outer lip semi-lunar, 

 the pillar lip nearly straight : columellar area flattened, and with a 

 wide callus which is somewhat encroached upon towards the middle. 



Relations and Distribution. — It is possible that Nerita pseudo-costata 

 is nothing more than a variety of the species next to be described, 

 occurring on a low horizon of the Inferior Oolite both here and in the 

 Cotteswolds. In Yorkshire it is confined to the Dogger, where it 

 must be rather rare, Mr. Leckenby's specimens being the best I have 

 seen. The aperture is so difli'erent from that of the Jurassic species 

 referred to Neritopsis, that we must agree with D'Orbigny in 

 referring it to Nerita. 



63. — Nerita oostulata, Deshayes=:NERiTA costata, Sowerby, 1824. 

 Plate IX. Figs. 10a, 10&. Enlarged twice. 



1824. Mrita costata, Sowerby. Min. Conch. Tab. 463, figs. 3 and 4. 

 1838. Nerita costtdata, Deshayes. Lam. Anim. sans vert. 2nd ed. vol. viii. p. 617. 

 1850. Nerita costulata, Deshayes. Morr. and Lye. Gt. Ool. Moll. p. 57, pi. ■viii. 

 fig. 6. 

 ,, Nerita pseudo-costata, D'Urb. op. cit. p. 114, pi. xv. fig. 3. 



Bibliography, etc. — Not having seen the reference in Deshayes's 

 work, I accept this name on the authority of Morris and Lycett and 

 of D'Orbigny. In the Prodrome this species is ranked as Bathonian, 

 whilst we have already seen how, in the Terrains Jurassiques, it has 

 been mixed up with Nerita minuta, Sow. Morris and Lycett (p. 57) 

 observe that " it has not been found in the Minchinhampton Great 

 Oolite, but occurs occasionally in the Inferior Oolite of that district." 

 There is no evidence, as far as I am aware, of its having been found 

 in the Great Oolite of this country, except perhaps at Stonesfield. 

 Phillips makes no allusion to this species in his third edition. 



Description. — Specimen from the Scarborough Limestone (zone 3), 

 White Nab. Herries Collection. 



Too much broken for accurate measurement, this fragment repre- 

 sents a shell about 8 or 9 mm. in height. In outline it resembles 

 N. pseudo-costata, except, perhaps, in being more depressed and in 

 the deepening of the sutural channel, but the ornaments are very 

 different. The ribs are finer, and more than twice as numerous as in 

 N. pseudo-costata : there is also a slight tendency to angularity in 

 the middle of the body-whorl, and a thickening of the ribs where 

 they pass over the widest part, as though prefiguring the formation 

 of a varix. 



Relations and Distribution. — This shell is sufficiently near to 

 Sowerby's type of Nerita costata from Anclifi" to be ranked with that 

 species, although there may be certain difi'erences which a very close 

 comparison might bring to light. A specimen from the Millepore 

 Kock, in Mr. Leckenby's collection, has more the appearance of 

 Sowerby's figure, and is to a certain extent represented by Morris 



