134 GASTEROPODA OF THE INFERIOR OOLITE. 



The aperture is trapezoidal, the outer lip considerably produced, and each of 

 the wing-digitations deeply channelled ; the canal is broad and comparatively short, 

 since it curves sharply in a direction opposite to that of the anterior digitation, and 

 to this circumstance much of the grotesque appearance of the shell (in common 

 with other members of the trifida-grouip) is due. This also terminates in a slight 

 expansion. 



Var. B. (Figs 6' a, 6' b.) 



Description : 



Length ..... 19 — 27 mm. 

 Spiral angle . . . .28° 



This form differs from the one last described in the comparative narrowness 

 of the spiral angle and in the height of the whorls of the spire in proportion to 

 their width. The slight differences of ornamentation are perhaps the result of 

 accident. We may compare these forms in some respects to Al. gracilis, Lycett. 



Var. C. (Fig. 6" a.) 



Description : 



Spiral angle about .... 40° 



This specimen, which is deeply embedded in matrix, may be somewhat deceiving 

 in appearance. It is shorter and more widely angled than the majority of speci- 

 mens, and would do very well to represent the " Ghenopus " Philippi of Dunker 

 and Koch. 



Relations and Distribution. — The Parkinsoni-zone of the neighbourhood of 

 Burton Bradstock has yielded nearly all our specimens of Al. Lorieri. There is a 

 specimen in the Bristol Museum (fig. 6 d), apparently a fragment of a large 

 specimen of this species. Elsewhere it is very rare, small, and in poor preservation. 

 Under such conditions Al. Lorieri or some member of the trifida-grouip may 

 occasionally be recognised in the Upper Division of the Inferior Oolite in the 

 Cottes wolds. Some specimens of the trifida-growp occurring in the Lincolnshire 

 Limestone may possibly belong here likewise, though not the forms from Great 

 Ponton (see PI. VII, figs 1 a, 1 b, and 2). 



