PULMONATA. 145 



tions smooth, longitudinally ribbed, transversely sulcated or cancellated ; spire short, 

 apex pointed, or more or less mammellated; aperture longitudinal, large, notched 

 at the base ; outer lip thin and sharp-edged in the young state, sometimes thickened 

 and plicated within at maturity ; columellar plaits more or less numerous, oblique, the 

 anterior plaits the largest. 



The genus Voluta, as characterised by Linnaeus, comprised the various shells in 

 which the columellas were plaited ; and it represented, in fact, as a French author* 

 has remarked, that group of genera which constituted Lamarck's family of columellata. 

 After numerous dismemberments, the genus was defined first by Bruguiere, and subse- 

 quently by Lamarck ; but, even as thus restricted, a more extended knowledge of the 

 animals has led to a still further curtailment of it by the withdrawal of the genera 

 Cymba (Brod.) and Melo (Brod.) 



The animal is of an oval form, with a large broad foot, extending beyond the shell on 

 every side ; the head is large, terminating in a short thick muzzle, and bearing 

 short triangulated tentacles, at the outer bases of which the eyes are seated. The 

 mantle, which is sometimes extended so as to cover the sides of the shell, is furnished 

 with two lobes in front, between which it is produced into a short siphon, bent back- 

 wards towards the shell. 



The recent Volutes are numerous, and many of them are of considerable size, and 

 distinguished by the beauty of their colouring ; they are, for the most part, inhabitants 

 of equatorial seas, frequenting sandy bottoms. In the fossil state they are equally 

 numerous ; they first appear in the earlier cretaceous deposits, and nearly twenty 

 species from the several formations of that epoch at Pondicherry, and in different parts 

 of Europe, have been described by Professor E. Forbes and by Dr. Mantell, Matheron, 

 D'Orbigny, and others. More than twice that number have been described by MM. 

 Lamarck, Deshayes, J. Sowerby, Nyst, Philippi, and other authors, from the Eocene 

 formations in Europe, and by Conrad and Lea from those of Maryland and Alabama, in 

 the United States ; while upwards of twenty species have also been described from the 

 more recent formations. 



On a comparison between the recent Volutes and their Eocene congeners, the pre- 

 vailing characters of the two groups may be stated, in general terms, to be that, in the 

 recent shells, the apex of the spire is broadly mammellated, the volutions are smooth or 

 longitudinally costated, and the columellar folds thick and prominent ; while, in the 

 fossil shells, the apex is generally pointed, the volutions for the most part are trans- 

 versely striated, sometimes cancellated, and the columellar folds are indistinct or com- 

 paratively feeble. These distinctions induced Mr. Swainson to separate the fossil 

 species under the generic name Volutilithes, taking Vol. spinosa (Lam.) as the type. A 

 cursory examination of the two groups, however, will suggest, I think, that a generic 



* C.d'Orbigny's ' Dictionnaire Universel d'Histoire Naturelle.' Art., Volute. 



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