100 PROCEEDINGS OF THE MA LACO LOGICAL SOCIETY. 



NOTE ON SWAINSON'S GENUS VOLUTILITHES. 

 By R. BtJLLEN Newton, F.G.S. 



Read Gth April, 1906. 



PLATE XII. 



I HAVE been induced to examine the history of Swainson's genua 

 Volutilithes in consequence of an enquiry made by Professor W. H. 

 Dall, of Washington, as to the vahie of Volutilithes pertusa, a new 

 species of fossil shell described and figured in the original account 

 of that genus. As a result of my investigations, I find that con- 

 ch ologists have hitherto associated the wrong type with Volutilithes; 

 and instead of that being the Conus spinosus of Linnteus (" Systema 

 Naturae," 1758, 10th ed., p. 715) it should be Lamarck's Valuta muricina. 

 A discrepancy of this kind has probably arisen through some difficulty 

 in obtaining the work known as " Zoological Ilhistrations," where 

 Swainson first described the genus in 1831. This author's later and 

 better known book of 1840, called "A Treatise on Malacology," 

 contained a second notice of Volutilithes, the form spinosus being the 

 first mentioned among a number of established species which were 

 included in the genus, and that which has ever since been regarded as 

 the type. This Linneean shell, it should be noted, is in no way 

 referred to by Swainson in the original description of Vohitilithes ; in 

 fact,' his earlier observations are not even alluded to in this subsequent 

 account of the genus. To further elucidate some of the points connected 

 with the subject, it is advisable to include here a transcription of the 

 full text of Swainson's first notice of the genus, so that students not 

 acquainted with the work in question may be in a position to consider 

 the matter for themselves. In making this extract I have inserted 

 certain references within square brackets for purposes of explanation 

 which are not in the original text : — 



"Volutilithes mdkicina. [PI. XII, Fig. 1.] 

 [Zoological Illustrations, 1831, ser. ii, vol. ii, No. 12, pi. liii, fig. 1.] 



Family Volutidse. Subfamily Volutinas. Nob. (Genus Fo/w^ffl, Lam.) 



Generic character. — Spiral whorls regularly and graduallydiininishing 

 towards the apex, which is always acute. Plaits of the pillar 

 numerous, always indistinct, generally evanescent, and sometimes 

 wanting. Nobis. 



Type. — Valuta musical is {?), Lam. 



Specific character. — Shell nearly fusiform, the base narrow and 

 smooth ; the upper part with longitudinal, subcostated, spinous plaits : 

 inner lip thickened, the last plait on the pillar very thick, and 

 separated from the others, which are slender and nearly obsolete, 

 by a deep groove. 



