98 MOLLUSCA FROM THE GREAT OOLITE. 



in having a plain surface ; it comes nearer in shape to Volvaria, but that has a truncated 

 or notched base, and crenated lip to the aperture, besides several plaits upon the columella." 



It has been proposed to form a new genus of it, to be called Cylindrites, but the 

 following species (A. acutus) having a conical spire, connects it with Actaon Noce. 'Min. 

 Con.' 5, p. 77, 1825. 



Notwithstanding their general resemblance to Actseon, we believe the species here 

 described to be generically distinct from the typical forms of that genus, and have there- 

 fore proposed to retain the name Cylindrites for them. 



The genus may be divided into two sections : 



A. Species with the spire elevated and acute. 



B. Species with the spire depressed and mammillated. 



The species belonging to the second section appears to pass into the Acteonellae of the 

 cretaceous system. 



A. Species with the spire elevated and acute. 



Cylindrites acutus. Sow. sp. PI. VIII, fig. 9, 9 a, b. 



AcTiEON acutus, Sow. 1824. Min. Con., t. 455, fig. 2. 



— — Morris. 1843. Cat. Brit. Fobs., p. 138. 



— — D'Orb. 1850. Prod. Paleont., p. 299. 



— — Bronn. 1848. Index Palaeont., p. 10. 



Testa subcylindricd, spird conicd, apice acuto, anfractibus (4) planis seu subconvexis ; 

 anfractu ultimo margine rotundato. 



Shell subcylindrical, spire conical, apex acute ; whorls (4) flat or slightly convex ; the 

 last volution rounded at its upper margin. 



Locality. This shell occurs in much greater numbers than all the individuals of the 

 other species put together ; it may, in fact, be considered as one of the most common 

 univalves in the Great Oolite near Minchinhampton. 



It occurs in the Oolite at Ancliffe, Wiltshire, whence the original specimens were 

 obtained, which are figured and described in the ' Mineral Conchology,' and Mr. J. de C. 

 Sowerby has kindly allowed us the use of the same for examination and comparison. 



Cylindrites cuspidatus. Sow. sp. PI. VIII, fig. 10, 10«. 



Action cuspidatus, Sow. 1824. Min. Con., t. 455, fig. 1. 



— — Morris. 1843. Cat. Brit. Foss., p. 138. 

 _ _ If Orb. 1850. Prod. Paleont., p. 299. 



— — Bronn. 1848. Index Palaeont., p. 10. 



Tornatella cuspidata, Deslongchamps. Mem. Soc. Linn, de Normandie, vol. vii, 



p. 136, t. x, figs. 25, 26. 

 — — Brown. Illust. Foss. Conch., p. 85, t. xliii, figs. 11, 12. 



