10b' SHELLS AND SHELL- FISH. "PART I. 



small tubercles. Their great distinction, liowever, 

 lies in the apex of their sj)ire, which always exhibits 

 the incipient developement, in the shape of tubercles, of 

 those spines which may be on the body- whorl. The com- 

 mon Cymhiola vespertilio(^fig. 9- h) is the type of the whole 

 genus. From these to the next division, represented by 

 Cym. pacifica, gracilis, &c., the gradation is easy and 

 natural. Nevertheless, these Australian shells constitute 

 a distinct division ; for they are known at once by the 

 greater prolongation of their spire, which is nearly equal 

 to their aperture, and by the majority being only tuber- 

 culated : the apex is always obtuse and slightly papil- 

 lary. Whether we should con- 

 sider the V. ancilla (Jig. 10.) 

 as a distinct type of form, is 

 uncertain, but it possesses a 

 peculiarity of aspect, which 

 seems to detach it from those last alluded to : the very 

 slender shape of its apex, however, smooths the passage 

 to the V. hraziliana of Solander, ■ — remarkable not only 

 for its pointed spire, and its ventricose shape, but from 

 possessing, like V. anguhta, only three plaits to the 

 pillar. It is clear that this, as well as C. mitis, are aber- 

 rant forms. 



(96.) In the next genus, Harpula, the form of the 

 apex, which is the main character of Voluta, became 

 somewhat variable in Cymhiola ; but in this genus it 

 is so uncertain, that it must be regarded only as of se- 

 condary importance. The numerous plaits, which ex- 

 tend the whole length of the pillar, are the most certain 

 distinction of Harpula, which is also a more numerous 

 genus than the last. Of the two primary types, one is 

 seen in H. vexillum, which is smooth, with a papil- 

 lary spire j the other, seen in H. hehrcea (fig. 12. b, in 

 p. 108.), is muricated, with the tip of the spire obtuse, re- 

 gular, conical, and hardly enlarged. There are, however, 

 other shells, obviously belonging to this group, which 

 will not arrange with either of these two divisions. One, 



