CHAPTER XXX: THE HAIRY-KEELED SNAILS 



Family Trichotropid^ 



Shell thin, turbinated; spire elongated; the keeled whorls 

 bearing an epidermal fringe of hairs; aperture roundish, angled 

 below; lip sharp; operculum laminated; foot elongated; head 

 broad; radula well developed; eyes on sides of tentacles. 



Genus TRICHOTROPIS, Bred. 



Characters of the family. Fifteen species in arctic waters. 



The Northern Hairy-keel (T. horealis, Brod. and Sby.) 

 has a thin little colourless spire, an inch long or less, with strongly 

 keeled whorls separated by deep but narrow sinuses. In life 

 there is a thin brownish epidermis which bears a row of hairs. 

 Dead specimens soon lose these hairs. 



Habitat. — Japan, Northern Europe, Greenland to Mass- 

 achusetts. 



T. cancellata, Hds., a trifle larger, checkered by longitudinal 

 ribs crossing the spiral ones, may be but the western form of 

 T. horealis. 



Habitat. — Alaska to Vancouver Island. 



164 



