MOLLUSC A OR UNIVALVES. 205 



71. Vermetus. — Shell thin, tubular, only 

 slightly twisted ; mouth round; lips 

 united. Animal, head indistinct, 

 having two tentacula with eyes at 

 the base ; foot cylindrical. — 1 spe- 

 cies. 



This is a very remarkable shell, 

 both in appearance and habits. The spire is 

 extremely irregular in formation, with the 

 whorls perfectly separated from each other; 

 and the animal, although of the tribe Tracheli- 

 poda, with a foot adapted for creeping, con- 

 tinues attached to one spot by the pointed 

 extremity of the spire. They may be found 

 in groups, twisted together in great numbers, 

 in the seas near Senegal. There is only one 

 species, the Vermetus lumbricalis. 



72. Magilus. — Shell ventricose; spire 

 short, consisting of three or four whorls ; aper- 

 ture longer than wide, without any notch, but 

 an angle at the base. The last whorl, aban- 

 doning altogether the spiral form, produces a 

 long tube, which is compressed laterally, es- 

 pecially on the side of the base of the shell; 

 aperture elliptical. Animal but little known; 



