270 



UNIONID^. 



with a quantity of other fresh-water and land shells, 

 all now found alive in the neighbourhood, as Pisidium 

 amnicumj Valvata ohtusa, &:c. &c. 



Order IV. UNION ACE A. 



Earn. 4. UNIONID^. 



Animal with mantle lobes free all round except at 

 the back, the hinder edge forming, when in 

 conjunction, two holes for the passage of the 

 water, food, and rejectamenta, the upper (i) 

 small, simple, the lower {a, a*, a**) bearded 



Fig. 65. 



li ■ ' a«« 



Anodon cygneus. 

 a, Lower siphon ; a*, a**, niagiiificd : b, U])per siphon; c, Foot. 



