14,2 



SHELLS AND SHELL-FISH. 



rhais, and the only example yet known is the pes-peli- 

 cani, or pelican's-foot strombus. That it has a close 

 affinity to Rostellaria columbata is evident from the outer 

 lip being dilated ; but then it has four lobes,, or rather 

 flattened and digitated processes, something similar to 

 Pteroceras chiragra ; and it deserves attention, that 

 these are the only two in the family which have the 

 basal channel assuming precisely the form, size, and 

 structure of the other processes of the outer lip : on the 

 other hand, it has no distinct lobe at the base, its mar- 

 gin is not inflected, and the upper part advances upon 

 the first spiral whorls ; in all which it shows an affinity 

 to Rostellaria. In its young state, however, (fig. 15. a) it 

 has quite a different appear- 

 ance ; for its form is then so 

 much like that of a young 

 Cerithium (b), that none 

 but a scientific observer 

 could detect the difference. 

 Equally related in this man- 

 ner to three different ge- 

 nera, we look upon this 

 type as connected to Ros- 

 tellaria on one side, Pte- 

 rocera on another, and to 

 the Cerithince on a third. 



All these affinities are more peculiarly apparent in its 

 three different stages of growth; so that, when quite 

 young, it is a Cerithium ; when the outer lip is half 

 expanded, it is a Rostellaria ; and, in adult age. it puts 

 on the very aspect of a Pterocera. Here we close our 

 evidence on the affinities and natural arrangement of 

 this family. 



(132.) Having now gone through the affinities, we 

 turn to the analogies of the Strombince. They are ob- 

 viously the typical division of the whole family; and, as 

 such, should represent within their own circle all the. 

 other divisions : this will be apparent in the following 

 table :-r- 



