PLATE XXI. 



the Voluta genus, the folds or plaits upon the pillar lip be considered, 

 this character is unequivocal. Linnaeus regarding this as one of its 

 most essential definitions, has overlooked the differences that prevail 

 in the structure of the spire and beaks, or includes them only as 

 distinctions of the different families into which his Volutse are divided. 

 Later writers differ upon this subject ; these differences are considered 

 by many as generical, and thus the Linnaean Volutae have become 

 separated into several distinct genera. In the shell before us, the 

 beak is lengthened or produced, and canaliculated ; and thus consti- 

 tutes in the classification of Lamark, a species of his Turbinella; 

 and is the shell in particular which he adopts as the type of that 

 genus. The character of that genus, as proposed by this Concholo- 

 gist, in his work entitled Animaux sans vertebres, is thus expressed, 

 Turbinelle (Turbinella) a shell turbinated or subfusiform, canalicu- 

 lated to the base, and having upon the column from three to five plaits 

 or folds of a compressed form and placed transversely. Murex 

 scolymus of Martini, Voluta ceramica of Lister, and Voluta capi- 

 tellum of the same author, are comprehended with the Linnjean 

 Voluta pyrum in this genus Turbinellus. 



It has been observed by De Montfort that Lamark has made a 

 group of those shells which accord with the above character, and which 

 he himself adopts with some small variations : according to this writer, 

 the genus Turbinelle, of which our Voluta Pyrum is considered as 

 the type, has the shell heavy, univalve, with an obtuse spire ending in 

 a nipple ; the mouth sloping and lengthened ; the pillar denticulated 

 with large equal folds or plaits, the outer lip strait and cut off, and 

 the base lengthened. 



After all the pains, h owever, which Lamark and other Conti- 

 nental Naturalists have taken to estabhsh the genus Turbinella, 



