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GASTEROPODA OF THE INFERIOR OOLITE. 



genus ; and Cossraann would still further enlarge its scope, since the latter author 

 refers several of the species described by d'Orbigny under Straparollus to 

 Solarium. Fischer, on the other hand, expresses doubts, observing that " the 

 numerous species [of Solarium] indicated in the Jurassic beds belong probably to 

 the genus Straparollus." Morris and Lycett described two species of Solarium 

 from the Great Oolite ; one of these (S. disculum) is, according to my views, a 

 species of Straparollus. 



The small shells from the Inferior Oolite which I refer to Solarium constitute 

 a fairly distinct group in that series ; and one of them, S. subvaricosum, may fairly 

 be regarded as a typical representative of the modern genus. 



255. Solarium pisolitictjm, sp. nov. Plate XXVI, figs. 6 — 8. 



Description : 



Diameter (average size) . . .4 mm. 



Height ..... 2*75 mm. 



Spiral angle .... 125°. 



Shell greatly depressed, moderately umbilicated ; nucleus oblique. Number 

 of whorls in the majority of specimens about five ; the earlier ones convex and 

 orbicular at the periphery, but the body-whorl is flatter and slightly angulated at 

 the periphery. As regards ornaments, the extreme apicals appear to have been 

 rather smooth, but a rich radial ornamentation is early developed, and this in the 

 body-whorl is slightly decussated spirally, so as to form a series of closely-set 

 nodose costa?. 



The body-whorl is relatively large and bicarinated, and the radial ornamen- 

 tation is carried as far as the anterior keel, which, as a rule, is less nodose than 

 the upper one. Base full, rounded, and produced ; it is provided with fine 

 reticulate ornaments, which are gathered into a ring of tubercles at the edge of 

 the umbilicus. • 



Aperture trapeziform or subpentagoual. 



Relations and Distribution. — This pretty little shell is easily distinguished 

 from the majority of the species referred to Straparollus by its regular spire and 

 sloping whorls, and also by the radial or axial character of the ornamentation. 



The very small specimen from Crickley (fig. 7) is believed to represent the 

 earlier stage, when the periphery is extremely orbicular. The very large one 

 (9 mm. in diameter) from the Pea-grit of Cleeve Hill may, on the other hand, be 

 regarded as a niegalomorph, where another whorl has been added. The usual 

 oi" average form is tolerably abundant in the Pea-grit at Leckhampton. 



