ALARIA. 137 



practically re-describes D'Arcliiac's species, and, doubtless, the points of resem- 

 blance with the Ponton fossil are tolerably close. In AJ. pvpseformis the shell is 

 still more depressed, and the position of the spines is very different from that of the 

 Ponton fossil. For all this we must hold that our var. spinifera closely approxi- 

 mates to Al. pupseformis, D'Arch., as defined by Piette. On the other hand, the 

 smooth or non-spinous variety of Al. pontonis is further removed from it. 



This species is rather characteristic of the Lincolnshire Limestone of Great 

 Ponton, but I have not met with it elsewhere in the Inferior Oolite. On the other 

 hand, it strongly resembles some of the Minchinhampton specimens of the 

 trifida-grouip, and thus affords another link uniting the Gasteropod fauna of 

 Great Ponton with that of the Great Oolite, both in the East of France and at 

 Minchinhampton. (See ' Great-Oolite Moll.,' PI. iii, fig. 11.) 



56. Alaria primigbnia, sp. nov. Plate VII, fig. 3. 



Description : 



Length . . . . .22 mm. 



Width of body- whorl to height of shell . . 42 : 100. 



Spiral angle about .... 34° 

 Shell fusiform, turrited. Opening of the spiral angle convex and obtuse. 

 Number of whorls about eight ; the apical and subapical whorls are without keel 

 and apparently smooth ; the last three whorls of the spire betray a very sudden 

 increase, and are sharply carinated about the middle. There is no longitudinal 

 ornamentation, and the spiral ornamentation, if ever it existed, is obliterated in 

 the only available specimen. The keels of the spire-whorls develop pointed 

 spinous swellings, which are very salient on the penult ; these do not occur in 

 axial order. 



The body-whorl presents but a moderate increase ; it is strongly bicarinate, 

 and rather excavated ; the base is very sharply marked off by the second carina. 

 The wing is scarcely, if at all, palmate; the posterior keel produces a vigorous 

 digitation, at first triangular in section, but becoming rounder, as it sweeps with 

 a sharp upward curve considerably beyond the apex. The anterior digitation 

 and canal-sheath are too much broken away for description. Other indications 

 wanting. 



Relations and Distribution. — This curious species, though founded on a unique 

 specimen, presents characters which easily separate it from any others heretofore 

 described. The uncompressed spire, and the unsymmetrical arrangement of the 

 spinous nodes, exclude this species from Spinigera, to which it has a certain 



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