90 SHELLS AND SHELL-FISH. PART I. 



genus Clavalithes Sw .* , several shells of an equally fusi- 

 form shape^ but having the tip of the spire papillary. 

 The shape of the FusincF, and the elongation of the body^ 

 render them very distinct from the PyruUncB, excepting 

 at that point of junction where the two groups are 

 united. Nothing satisfactory is known^ so far as we can 

 discover, of the general nature of the animals. 



(78.) The Fusinm being thus defined as a whole, we 

 may now proceed to the series of the genera, and their 

 peculiarities. — 1. In the first or typical genus Fusus, 

 the spire and channel are both very much lengthened_, 

 and remarkably slender ; the outer lip generally cre- 

 nated, — the indentations corresponding with the internal 

 striae, — 2. Chrysodomus, distinguished from the last by 

 the comparative shortness of the basal channel_, and the 

 ventricose or enlarged shape of the body-whorl. The 

 beautiful orange mouthed wilk of England is a typical 

 example ; and the few others^ now known^ are all of a 

 large size, and chiefly found in northern seas_, where they 

 represent the more elegant Fusci of tropical latitudes : 

 the outer lip is always thin and smooth. — 3. Leiostonms, 

 where the body -whorl is still larger than the last, while 

 the spire, although remarkably short, is acutely pointed ; 

 the inner lip is highly polished, and the contracted base 

 of the shell is equal, or rather longer than the aperture ; 

 the outer lip, like that of Chrysodomus, is thin and 

 sharp, but thickened within. All the species of this 

 form we have yet seen are fossil, of which the Fusus 

 bulbiformisf is one of the best and most common types: 

 the outside and the mouth of these shells are always 

 smooth ; hence their generic name. — 4. The next genus 

 we have named Strepsidura, from the twisted shape of 

 its tail or channel : the form of these shells is very much 

 like the last, but the base or channel is equal with the 

 spire, and is turned in an oblique direction; the outside 



* We had originally called this genus ClnveUa ; but as this name may be 

 thought too closely resenihling, in sound, those of ClavagcUa and Clavalula 

 (Lamarck), we now substitute another, — more appropriate, indeed, as all 

 the species we have yet seen are fossil. 



t Ency. Mcth. pi. 428. fig. 3. 



