INSTITUTE OF SCIENCE, PHILADELPHIA. 8 1 



to his J^ohitifusiis typns, an inapplicable name, which is misleading and cannot 

 be retained. It is quite possible that this is the adult of A. obtusa Emmons, 

 though we have not yet a connecting series. This species has the aspect of A. 

 inuiabilis, but has a strongly curved canal, is much smaller when adult, and 

 has the two plaits quite large and strong in what seem to be adult specimens. 

 This feature, if permanent, would conflict with the characteristics of the rest 

 of the group, but more material is needed to decide the question. 



The undescribed species is represented by a fragment in the Philadelphia 

 collection, but as it has lost the nucleus and base, it may prove to be a Sca- 

 pliella when a complete specimen is secured. 



In the Pliocene A. dnbia persists, and is also a member of the existing 

 fauna, together with two species not known as fossils, A. robusta and A. Goiild- 

 iana Dall (PI. 7, figs. 2, 5), on the southeastern coast of the United States. 



The fragment upon which Conrad founded his Megaptygma sinuosa has a 

 general resemblance to Scaphella Trenliolmii, but shows a much more curved 

 base and three, or possibly four, plaits. These have the aspect of being dis- 

 eased, and their characters may eventually prove pathologic. There is no 

 doubt, whatever it is, that it ranges somewhere in the Scaphelloid series. 



There is some reason for thinking that the genus Halia Risso, Pliocene 

 and recent in European waters, may be the last term of degeneration in this 

 direction, having lost all its plaits and holding much such a relation to Auri- 

 nia as does Guivillea of Watson, also a deep-water and degenerate type. 

 Provocator Watson should, from its published characters, belong in this vicin- 

 ity; its posterior sinus, as in Harpa, is not homologous with that of Pleiiro- 

 toma, but simply allowed the passage of a fold of the mantle by which the 

 glaze covering the spire was deposited, much as in Liopepbim. 



Genus CYMBA Broderip & Sowerby, 1826. 

 Type Cymba ( Voluta) olla Linn6, European seas. 



This group is distinguished by its viviparous habit, its superficial glaze, its 

 animal too large to fully enter the shell, its spire uncrowned by a row of spires, 

 and its mammiform, enormous secondary nucleus. The pillar is twisted, the 

 shell thin, elongate and rather narrow (compared with Melo), the suture, or the 

 whorl near it, usually channelled or turrited, and the spire nearly involute. 



The synonymy is confused and I shall not attempt an exhibit of it here, 

 but I believe the name of Cymba to be entitled to acceptance. 



It is known only in the later Tertiary beds and has never been an inhabit- 

 ant of North America or the adjacent seas. 



Subgenus Eucymba Dall. 

 Plate 7, figure i. 

 Type E. ocalana Dall, Upper Eocene of Florida. 



Shell shaped like Fulgiir when young, with a slender, long canal and fig- 

 shaped body, the adult subglobular, large ; nucleus lenticular, large, laterally 



