MONOCEROS. CONCHOLEPAS. HAKPA. 89 



the chalk-cliffs of the coast ; the colour varies, 

 sometimes white, at others yellowish. 



" I shall describe a species of the singular 

 genus Monoceros, by which you will scarcely 

 fail to recognise it. 



^' The columella is flattened like Purpura 

 pattda; just within the outer lip is a row of 

 small teeth ; but the principal peculiarity is a 

 process, or horn, near the outer part of the lower 

 lip, and close to the canal, from which the genus 

 derives its name Monoceros, one-horn. It is 

 brought from the seas of America. 



" Coiicholepas Peruviana, the only species, 

 is also a remarkable shell. The aperture is very 

 large, almost equal to the shell itself; the spire 

 is near the edge ; the outside is marked with ribs, 

 or costse ; there are two short teeth on the right- 

 margin. This shell was placed among the 

 Patella. 



" The beautiful genus Harpa, harp-shell, is 

 remarkable for its elevated ridges on the back of 

 the shell, its large aperture, and its fine colour- 

 ing. They are East Indian shells. H. ventri- 

 cosa is a common species. H. nobilis is very fine, 

 and also H. costata. 



" Equally well known are the Tuns, Dolium, 

 by their globose form, the right-margin toothed, 

 and a canal below. They reach a large size, and 

 are light shells in proportion to their bulk. 



