130 GASTEROPODA OF THE INFERIOR OOLITE. 



Relations and Distribution. — In some respects this species has more resemblance 

 to Al. lavigata, M. and L., but the position of the principal spine, the comparative 

 straightness of the canal, the keel in the penultimate, and the well-developed spiral 

 lines, should, if Piette's description is to be accepted, distinguish Al. sublavigata 

 from the Great-Oolite species. 



Occurs sparingly in the Inferior Oolite of North Dorset, and chiefly in the 

 Sowerbyi- or concavus-bed. The variety shown in figs. 3' a and 3' birom Bradford 

 Abbas has a smooth outline, and but for the position of the spine might almost 

 be referred to Al. myurus. The specimen, 3 b, is from the Yorkshire Dogger. 



52. Alaria myurus, Deslongchamps, 1842. Plate VI, figs 4 a, 4 b, 4 c. 



1842. Kostellabia mtueus, Deslongchamps. Mem. Soc. Linn. Norm., vol. vii, 



p. 176, pi. ix, figs. 23—25. 

 1850. Pteeoceea — IfOrhigny. Prod., i, p. 270. 



1864. Alaeia myurus, Eud. Besl. Piette, Cont. de la Pal. Franc., p. 30, pi. ii, 



figs. 8—11, and pi. vi, figs. 11, 12. 

 ? — — Desl. Lycett, Suppl., p. 122, pi. xli, fig. 13. 



? — — — Tawney, Dundry Gasteropoda, p. 11. 



Bibliography, fyc. — Deslongchamps' species is a fossil of the " Oolithe ferrugi- 

 neuse " (Calvados), and belongs consequently to the Upper Division of the 

 Inferior Oolite. It was said to be rare, but Piette qualifies this by stating that 

 it is tolerably numerous. Al. myurus is not quoted in Morris's Catalogue of 

 British fossils. Mr. Tawney drew attention to some imperfect specimens from 

 Dundry ; none of these show very characteristic features. 



The value of the difference between Al. myurus, Desk, and Al. Icevigata, M. 

 and L., is a question that has been much debated. In 1884 (' Geol. Mag.,' p. 196) 

 I pointed out that the absence of striae, on which alone Morris and Lycett based 

 their distinction, was, under the circumstances, of no value whatever. This was 

 written before I had read Lycett's note in the Supplement, where, in consequence 

 of his having discovered strise in Al. lavigata, he withdrew it as a distinct species. 

 Laube (' Gast. von Balm,' p. 24) endorses this union of Al. lavigata and Al. myurus. 

 Piette, on the other hand, says that, although Al. myurus is near to Al. lavigata , 

 it has the spire more ventricose and less elongate, it is striated almost throughout 

 and the penultimate is subangular. Cossmann (' L'fitage Bathonien en France,' 

 p. 164), alluding to the remarks of Lycett in the Supplement, and of Laube, is 

 disposed to agree with Piette, and separates them as distinct species. On the whole 

 it seems to me that the differences are slight, but apparently constant according 

 to horizon ; hence, although the original difference noted by the authors of 



