Lamarck'9 Genera of Shells. 61 



4th Family. 

 Columellaria. (5 genera.) 



No canal at the base of the aperture, but a more or less dis- 

 tinct subdorsal notch, and folds on the columella. 



The shells of this family are entirely without any canal ; their 

 essential characters are the plaited columella, and the notch at the 

 base of the aperture. 



1. Columbella*. 



Shell oval, spire short : base of the aperture more or less 

 notched ; no canal. Columella plaited. Aperture contracted by 

 a swelling on the inner side of the right lip. 



The shells of this genus are short, small, and of considerable 

 thickness ; often striated transversely, and of very various colours. 

 They are marine, shore shells, and are distinguished from the 

 volutae, by the swelling on the inner side of the right lip, and by 

 their having a small operculum. 



Type. Columbella mercatoriaf. (Voluta mercatoria. Linn.') 



Shell ovate-turbinated ; transversely sulcated, white, painted 

 with small, reddish brown, transverse, subfasciculated lines, some- 

 times banded; lip toothed within. Coasts of Goree. PI. v. 

 Fig. 193. 18 Species. 



2. Mitral. 



Shell turrited, or subfusiform ; spire pointed at the summit ; 

 base notched ; no canal. Columella transversely plaited ; plaits 

 parallel, the lower ones the smallest. Columellar lip thin, and 

 resting on the columella. 



Distinguished from the voluta?, by the summit of the spire being 

 quite pointed, and not terminated by a mammella, and by the 

 columellar plaits gradually lessening towards the base. The colu- 

 mellar lip is sometimes visible only near the base of the columella. 

 The mitroe are found in the seas of warm climates ; they are 

 agreeably varied in their colours, and sometimes are covered with 

 an epidermis. They probably have no operculum. 



* Dim. from columba, a dove? f Connected with traffic. 



X A Mitre. 



