92 TRACHELIPODA. 



Genus 40— TURBO Linnceus. 



Generic Character Shell conoid, or sub-turriculated ; 



aperture entire, round, margin of outer lip disunited ; colu- 

 mella arcuated, depressed, but not truncated at the base ; 

 aperture provided with a testaceous operculum. 



This genus has recently been subdivided into a great number of 

 genera, one of which contains our common Periwinkle, Littorina lit- 

 torea. 



Turbo setosiis — The Bristly Turbo. Plate XII. fig. 

 17. Thick, transversely and deeply sulcated, and longi- 

 tudinally striated ; spire short ; volutions rounded ; lip 

 crenulated ; variegated with white, green, and brown; in- 

 side perlaceous. Two inches long. Inhabits the Indian 

 seas. 



Genus 41. --MONODONT A.— ZamarcA. 



Generic Character. — Shell ovate or conoid; aperture round 

 and entire ; outer lip disunited from the body at top ; colu- 

 mella arcuated and truncated at the base ; aperture provided 

 with an operculum. 



Monodonta coronaria. — The Thick-lipped Monodon- 

 TA. Plate XII. fig. 10. Covered with numerous, small, 

 scabrous, acute, turbercles ; outer lip very thick ; apex 

 blunt, white ; the coluiijella reddish. One inch and a quar- 

 ter long. Inhabits the Chinese seas. 



Genus 42 TROCHUS Linnceus. 



Generic Character. — Shell conical; spire elevated, some- 

 times abbreviated; aperture transversely depressed; margin 

 of outer lip disunited from the body at the upper part ; 

 columella arcuated, more or less oblique at the base ; aper- 

 ture provided with a horny operculum. 



Trochus Zizyphinus. — The Zizyphine Trochus. Plate 

 XII. tig. 2. With strong transverse striae ; colour livid, 



