258 



MTiall tubercles, besides the thin sharp tooth at the base. 

 From the growth of the tooth, in proportion to the in- 

 crease of the shell, an internal rib is formed, and some- 

 times a corresponding groove on the exterior. It is 

 known to English collectors by the trivial name of the 

 Unicorn Scoop. Lamarck mentions five species, but a 

 greater number is known. The type of this genus, M. 

 cingulatum, possesses some singularities; its columella 

 is not smooth, but irregularly plaited or wrinkled, and 

 the tooth does not extend within the interior of the 

 whorls, as in the other species enumerated by Lamarck, 

 but appears affixed only at the edge of the lip. 

 Monoceros cingulatum Monoceros striatum 



imbricatum • • » glabratum 



Monoceros crassilabrum. 



CONCHOLEPAS. 



PATELLA LEPAS. LhllKBUS. 



Sowerbys Genera, No. 6, pi. 1. 



This very singular shell has hitherto always been con- 

 sidered a Patella, from which it is very distinct in many 

 respects, but particularly on account of its having an 

 operculum. Bruguiere classed it with the Buccina, in 

 consequence of the slight notch at the base: but other 



