125 



however inferior in size to most of the members of that 

 exceedingly interesting though extinct race. 



They are spiral, with adextral mouth, which is semi- 

 lunate, or elliptic, and entire. 



The animal possesses a broad head, with a pair of 

 long tentacles, the eyes being [as in other branches of 

 Limnoeade] placed at their inner bases. 



An aquatic race, feeding upon water plants. 



Planorbis cornkus [The Horny Coil Shell], Linnceus. 

 Figures 89 and 90. 



Described by Lister, in 1678. 



This species is the king of the Planorbis tribe, beinf 



larger than any other in the waters of Great Britain 



It is thick, strong, nearly three times as broad as it is* 



high, and has five deeply divided ventricose codtoIu- 



M 2 



