232 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



longit. totius | sequans; labrum incrassatum, rufo et albo maculatum, 

 vix expansuui ; columella vix arcuata, lajvis, callo albido supra ad 

 insertioneru incrassato induta, plieis obliquis sex (tribus superioribus 

 fere obsoletis) instructa. Long. 57, diam. ruaj. 29uiui. ; apertura 

 38 mm. longa, 13 lata. 



Ilab. — Ten miles off Durban, Natal, 40 fathoms. 



This species is closely allied to V. /estiva, Lamarck, which has also 

 been recorded by Mr. (t. B. Sowerby 1 from the coast of Natal. It 

 differs, however, from that species in its smaller size, smaller and less 

 globose protoconch, the greater concavity of the upper part of the 

 whorls, the acute tubercular character of the costae at the angle, 

 the thickened labrum, and the absence of the characteristic black 

 mark at the upper and lower ends of the columellar callosity. The 

 columellar folds in V. /estiva are about ten in number, of which the 

 seven upper ones become gradually obsolete. In the present form, 

 however, they are only six in number, three 

 being scarcely observable. In V. /estiva the 

 longitudinal ribs are roundly nodose above and 

 produced more or less distinctly to the base or 

 anterior end of the body-whorl. On the other 

 hand, in V. Ponsonbyi they are very acutely 

 produced above, giving the whorls a very pretty 

 coronated appearance, and upon the last whorl 

 they merely take the form of very prominent 

 tubercles, the rest of the surface being smooth 

 and non-costate. These tubercles are ten to 

 twelve in number, and marked near the top with 

 a dark spot, and the costae upon the penultimate 

 and antepenultimate whorls are twelve or thirteen 

 in number. The coloration of this very handsome 

 shell is very different from that of V. /estiva, Voluta Ponsonbyi, n.sp. 

 the transverse pale zones, which are crossed 



by numerous curved irregular brown lines, being a very noticeable 

 feature. In all the figures of V /estiva the protoconch is globose 

 and papillary. In the present species it is much smaller, less globular, 

 and consists of three instead of two whorls. It measures only 2-5 mm. 

 in diameter, whereas in a specimen of V. /estiva in the Museum 

 collection the diameter is nearly 5 mm. "With regard to the difference 

 of size between this species and V. /estiva it should be noted that it 

 is not due to age, for the shell - now described is evidently mature, 

 its adult condition being indicated by the thickened outer lip and the 

 final ascent of the last upon the penultimate whorl. 



I have much pleasure in naming this handsome species after 

 Mr. J. H. Ponsonby, as a mark of appreciation of the service he has 

 rendered in elucidating the shell fauna of South Africa. 



1 " Marine Shells of South Africa," Appendix, p. 8. 



2 Since this description was written, a second beautiful specimen in Mr. E. R. Sykes' 



collection has been kindly shown to me, which is similar in every respect. 



