CHAP. III. THE PYRULIN.E. 85 



cies. 2. Ficula, where the great elongation of the canal 

 is still preserved, but the shell is differently formed, 

 and its substance very thin. The body-whorl is more 

 or less ventricose, and without any spines or protube- 

 rances; the spire also is so small and depressed, that the 

 shell has very much the appearance of a Bulla, length- 

 ened out at the base ; and there is little or no indica- 

 tion of even the thin glazing which forms the inner lip: 

 such, at least, are the characters of the typical species *, 

 which are few and easily recognised. In P. caudata'f, 

 a new modification of form begins to be developed, — 

 slightly, indeed, but quite sufficient to leave us in no 

 doubt as to the characters of the next genus : this 

 species has the general form of Ficula, but the spire is 

 somewhat more elevated, and the inner lip is so much 

 developed that it begins to have a defined margin at its 

 lower part ; the body-whorl loses nothing of its ventri- 

 cose or inflated aspect ; and the shell is remarkably 

 thin and brittle. It is a fact highly interesting to our 

 present purpose, that there is a shell in almost all re- 

 spects similar to the Ficula caudata (of which it has 

 been described as a variety), but which has a decidedly 

 short canal. Here, then, is the point of junction so 

 desirable to be established between Ficula and our new 

 genus Rapella, typically represented by the Ficus rapa 

 of authors.;}; The spire, although pointed, is still re- 

 markably short, and almost turbinated ; the body-whorl 

 equally ventricose with the last, but the lower portion 

 is no longer lengthened — it becomes very short, and, 

 by the more sudden contraction of the aperture at the 

 basal point, the canal becomes so very small as almost 

 to be obsolete. From the absence of the inner lip in 

 the last two genera, the shells have no umbilicus, but in 

 Rapella both these characters are apparent ; the umbi- 

 licus is usually very large, while the base of the inner 

 lip is partially or entirely reflected over it. The sub- 

 stance of these shells varies according to the species, and 



* Pyrulajicus Lam. Eiicv. Meth. pi. 431. fig. 1.; fig. 2. is another species. 

 ■*■ Ency. Meth. pi. 436. fig I.e. % Ibid. pi. 434. fig. 1. 



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