DIVISIONS OF THE MITRES. 



129 



genera -of the volutes ; and they may be thus briefly 



characterised from their 

 1 4^*«s8^^^^ ,,s*^sr si^ells. The most typi- 



cal is — 1 . Mil ra, where 



\ i^^^^^^^^^^--- ^^^ basal whorl is some- 

 .^^^^^^i®(9^SB^==- what ventricose, and the 

 aperture has no inter- 

 nal groove. 2. Tiara 

 {fig. 14.);, having the 

 basal whorl contracted, 

 and the internal groove distinct; — this is the sub- typical 

 genus. The 3d, or next, Mitrella, resembles the olives 

 in being smooth, and in having the base of the pillar 

 thickened, with the plaits very much projecting. In 

 the 4th, or Conceheli^, the spire is very short, the plaits 

 numerous, and sometimes indistinct: whereas, in the 5th, 

 or Mitreola, the upper plaits are smallest, the outer lip 

 inflected and sometimes toothed, and the spire slightly 

 papillary. As all these peculiarities will be detailed in 

 the next division of our volume, we shall here only make 

 a few general observations on the contents of the genera ; 

 and first, with regard to 



The Analogies of the Volutins and the MiTRiNiE. 



Genera of the 

 Mitrince. 



MlTRA. 



Analog/'cal Characters. 



Tiara. 



Mitreola. 



CONCEHELIX. 



MiTUliLLA. 



r Body- whorl never contracted at 



< the base ; the whorl 

 L retedor anguJated. 

 fShell turreted; body-whorl con-~| 

 I tracted in the middle; the | 

 i whorls nodulous or sub-coro- J> 

 I nated, or carinated, rarely | 

 L. smooth. J 



The upper plaits on the pillar^ 

 smaller than those in the mid- 5- 

 die ; spire sometimes papillary, j 

 ( Spire very short ; plaits very slen- ^ 

 3 dor, sometimes obsolete ; sur- f 

 j face generally reticulated orf 

 (. striated. 3 



r Smooth, generally polished; the 



< lower plaits smaller than the 

 C upper. 



ntracted at! 

 s never tur- > 



Genera of the 



VolutincE. 



Cymbiola. 



IIarpila. 



VOLUTILITIIE! 



.SC A PI I F.I.I 



