XXXUl 

 UNIVALVE SHELL. 



MhH. Sjjl. Li,:. Syjl. 



Tentacula linear 4 eyesat the tip of the longed Helix. Ilehx. 



Tentaculd linear 2 eyes at the tip Vertigo. Turbo. 



eyes at the bafe exterior Nerita. < ^ j ' 

 Tentacula fetace- J J-u ■: 



ous 2 i eyes at the bafe interior Planorbis. \ V> iV ' 



I ^ l_i3ulhi. 



[_eyes at the bafe pollerior Valvata. Heli.x. 



Tentacula trunca- J eyes at the bafe interior Ancylus. Patella 



ted 2 l^eyes at the bafe pofterior Carychium. Turbo. 



Tentacula trian- f ^ i i r ■ ^ • -d • tt i- 



1 „ -s eyes at the bale mterior ouccinum. Helix, 



guiar 2 \ ^ 



fa 



TO THESE MAY BE ADDED, 



Tentacula fetaceous 2 

 Feelers 2 one plumofe 



> eyes at the bafe Turbo. 



The lall divifion does not belong to the Mullerian fyf- 

 tem, but is introduced for the purpofe of fliewing ano- 

 ther fcrong fub-divifion by the animal ; and which would 

 include the Valvata of Muller. It is very extraordi- 

 nary, that author did not avail himfelf of fuch a ftrong 

 mark of diftinftion for his generic charafter olValvata ; 

 whereas, he has only ufed it fpecifically by calling the 

 only fpecies he knew crijlata. To this, however, might 

 be added, his Nerita pifcinalis , the Turbo fontinalis oi 

 this work ; which is alfo crelled or plumofe. 



Befides what has already been remarked, that fome 

 of this clafs are hermaphrodite, and others of different 

 fexes ; it will be found alfo that fome are oviparous, and 

 others viviparous : and it is remarkable, that all thofe 



e 2 witii 



