ANCILLA 



Lam. — Syst. des Anim. sans Vert. p. 75. 



TESTil oblonga^, subcylindrica;, spird brevi^, non 

 canaliculata. Apertura elongata^ basi emargi- 

 nata^ effusa. Appendix tumida et obliqua ad 

 basim columella. 



We have no hesitation in retaining Lamarck's original 

 name for this Genus ; partly because we wish to avoid un- 

 necessary innovation, and further, because we think it is 

 sufficiently different to be easily distinguished from MUUer's 

 Ancylus, 



In general form the shells of this Genus are oblong 

 and subcylindrical, they have a short spire^ seldom exceed- 

 ing a third of the whole length of the shell, and the volutions 

 are not separated from each other by a canal, as they are in 

 Oliva, but the line of separation is generally hidden by an 

 enamel-like shelly deposition which extends far beyond it, 

 and sometimes covers the whole upper part of the shell. 

 The aperture is elongated, wider at its lower than at its 

 upper part, and notched at its base. The Columella is 

 smooth, with an oblique, tumid, generally striated ap- 

 pendage, or varix at its base. The whole shell is very 

 smooth and shining, and, as we believe, destitute both of 

 epidermis and operculum. 



The only Genera with which this can be confounded, 

 are Terebellum and Oliva; the striated, tumid varix dis- 

 tinguishes it from Terebellum; and it wants, as before 

 observed, the canal which separates the volutions in Oliva. 

 Only a few recent species are known, they are placed 

 among the Linnean Voluta ; but though the animal is not 

 known, there is reason to believe, that its mantle is ex- 

 tensible over the whole or greater part of the shell, if we 

 may judge from their perfect smoothness. The small num- 



