102 PROCEEDINGS OF TUE MALACOLOGICAL SOCIETY. 



deposits of botli England and France. As far as can be ascertained, 

 this species was never previouslj^ occupied for the type of another 

 genust^ so that it is clearly available for recognition as the type of 

 Volutilithes. It is certain, also, that Swainson was anxious to 

 emphasize the importance of Lamarck's shell, since he headed the 

 whole history of his new genus with " Volutilithes muricinar 



The late Paul Fischer also used the same Lamarckian shell for the 

 type of EopseplixBa, consequently this will now become a synonym of 

 Volutilithes. In all Gastropods the details of the protoconch are of 

 essential value for purposes of classification, and particularly among the 

 Volutidae, where so much variation has been observed by Cossmann, 

 Dall, Crosse, and other authorities. This character is very distinctive 

 in well-preserved examples of Volutilithes muricina, especially those 

 obtained from the Parisian Eocene, the protoconch consisting of two 

 smooth mammillated whorls surmounted by a laterally situated, 

 conically pointed nucleus. 



Such a change of types as is here suggested unfortunately renders 

 a long list of species, hitherto regai'ded as Volutilithes, without 

 a generic name. Many of these shells are referred to by M. Cossmann 

 in his comprehensive treatise already alluded to ("Essais," etc.), at 

 the head of which stands the Eocene Voluta [ Conus^ spmosa, Liunseus, 

 Swainson's type of his later Volutilithes. To embrace this group of 

 species under the same type it is proposed to replace Swainson's 

 Volutilithes of 1840 by the new name of Volutospina. 



The third shell referred to as belonging to Volutilithes is the 

 new species, pertusa, which is said to exhibit " the grey tinge of the 

 London Clay fossils." This term "London Clay," as used in 

 Swainson's time, was applied to most of the fossiliferous clays found 

 in the Lower Tertiary rocks of the London and Hampshire Basins, and 

 not as at present restricted for a particular geological horizon. It is 

 therefore not surprising to find, after a careful comparison of the 

 fossil Volutes in the " Frederick Edwards " and other collections at the 

 British Museum, that this Volutilithes pertusa is the same shell as was 

 figured by J. Sowerby as Voluta costata in the " Mineral Conchology," 

 1821, vol. iii, pi. ccxc, figs. 2, 4, but which, differing from Solander's 

 shell (represented by fig. 1 of Sowerby's plate) of an earlier date and 

 similar name, was subsequently included by Edwards in his Voluta 

 humerosa^ (Mon. Palaeontog. Soc, 1854, p. 171, pi. xxii, fig. 6), a 

 characteristic Upper Eocene species found in the Barton Clay of 

 Hampshire, and which is apparently unknown in the corresponding 

 deposits of the Paris Basin. 



It should be noted that the original figures of V. humerosa of Edwards do not 

 clearly exhibit the characteristic spiral striations which are so well expressed in 

 the types as well as in all other examples of the species. This ornamentation, 

 as in Swainson's figures of pertusa, is mainly confined to the sutural and basal 

 areas of this shell, thus differing from Solander's V. costata, where the entire 

 surface of the volutions is transversely liueated. There are, of course, other 

 distinctions to separate these species, but it is not necessary to enlarge upon them 

 at the present time. 



