130 GASTEROPODA OF THE INFERIOR OOLITE. 
Relations and Distribution —In some respects this species has more resemblance 
to Al. levigata, 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. sublevigata 
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’ b from Bradford 
Abbas has a smooth outline, and but for the position of the spine might almost 
be referred to Al. mywrus. The specimen, 3 6, is from the Yorkshire Dogger. 
52. ALaRIA MyuRUS, Deslongchamps, 1842. Plate VI, figs 4 a, 4b, 4 ¢. 
1842. RosreLLarta Myurus, Deslongchamps. Mém. Soc. Linn. Norm., vol. vii, 
p. 176, pl. ix, figs. 23—25. 
1850. Prrrocers _— D’ Orbigny. Prod., i, p. 270. 
1864. Atarta myurus, Hud. Desl. Piette, Cont. de la Pal. Frang., p. 80, pl. 1, 
figs. 8—11, and pl. vi, figs. 11, 12. 
? — — Desi. Lycett, Suppl., p. 122, pl. xh, fig. 13. 
? — 7 — Tawney, Dundry Gasteropoda, p. 11. 
Bibliography, §c.—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. mywrus 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. mywrus, Desl., and Al. levigata, M. 
and L., is a question that has been much debated. In 1884 (‘ Geol. Mag.,’ p. 196) 
[ 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 strie in Al. levigata, he withdrew it as a distinct species. 
Laube (‘ Gast. von Balin,’ p. 24) endorses this union of Al. levigata and Al. mywrus. 
Piette, on the other hand, says that, although Al. mywrus is near to Al. levigata, 
it has the spire more ventricose and less elongate, it is striated almost throughout 
and the penultimate is subangular. Cossmann (‘ L’Htage 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 
