INSTITUTE OF SCIENCE, PHILADELPHIA. J \ 



The early Cymba forms are so poorly preserved, as a rule, that details of the 

 nucleus are very difficult to make out with confidence. The ancient forms 

 differ from the recent Cymba in having a flattish apical nucleus and a solid 

 straight pillar, for which reason I separate them subgenerically as Eucymba. 

 They seem, when young, to have a much more slender canal, and when adult 

 to be of a more globular shape, and hence with more horizontal plaits than the 

 recent Cymba. 



The early whorls and nucleus of Lapparia Conrad (PI. 6, fig. 6) are un- 

 mistakably caricelloid and the shell belongs to the VobitidcB, though the species 

 have been referred to Mitra, Fasciolaria, Cordieria, etc. They have a very 

 Mitra-XxVe. aspect, apart from the nucleus, and range- from the Middle to the 

 Upper Eocene. The nucleus of Valuta {Scaphella) angidata, when cleared of 

 callus, appears to have been caricelloid, but may possibly have wanted a spur. 



We may now consider the group systematically in the order of its de- 

 velopment. 



CRETACEOUS FORMS. 



The material is not available for a complete statement of the characters 

 and distribution of the Cretaceous Vohitidce. Three groups are distinguish- 

 able in the later Cretaceous forms of North America, most of which are most 

 fully developed in the Ripley group, which forms the transition between Cre- 

 taceous and Eocene in the East, and the Chico-Tejon series, which are in a 

 similar situation west of the Sierra Nevada, 



Genus ROSTBLLITES Conrad, 1S55. 

 Type R. texana Conrad, Eagle Pass, Te.xas. 



The type is probably identical with Rostellaria indurata Conrad (1S49), 

 from the Chico series of Oregon. The group was subsequently named ]'olu- 

 toderma Gabb (1876), and species belonging to it have been referred to Volu- 

 tUithes, Fidgoraria, Fasciolaria, etc. It is characteristic of the Cretaceous 

 formation. American species referable to it are R. texana Conr., R. indurata 

 Conr., R. ( V?) NavarroeJisis Shumard, R. Gabbii White (=Navarroensis Gabb 

 non Shumard). In Prof Whitfield's unpublished report on the Gastropods 

 of the Cretaceous Marls of New Jersey, which he has generously allowed me 

 to consult, the following species are referable to this genus : R. ( Volutodermd) 

 biplicata Gabb, R. (V.) ovata Whitfield, R. nasuta Gabb, R. angida Whitf, R. 

 texturata Whitf, R. Abbotti Gabb, R. biconica Whitf, and R. ( F!) intermedia 

 Whitf As many of these names depend upon internal casts, it is probable 

 that the number of species, if proper data were available, would prove to be 

 considerably smaller, especially as those species which are well known are 

 known to be very variable in form. 



In the Cretaceous of Brazil Volutilithes alticostatus White, and V. radida 

 Sby., may possibly be related to this group, but the latter is more like true 

 Volutilithes. 



