THE FAMILY NAIADES. 



29 



IT: 



H 

 o 



O 

 1^ 

 1^ 



I 



b 



tn 

 o 



OVAL. 



divaricatus. Lea. 



Burroughianus. Leu. 



simus. I^ea. 



corrugatus. Lam. 



Mya corrugata, M'nller. 

 Wood. Dill. 



Chem. Gmel. 



Mya rugosa. Gmel. Wood. Dill 



Mya nodosa ? G7nel. Wood. Dill. 



Mya spuria. Gmel? Wood. 



Unio spuria. Lam. 



Unio triradiata. /;? " Museum^'' at Paris. 



Niloticus. Fer. 



Mya pictorum. Forkael.'* 

 Egyptiacus.t Cailliaud. Fer. 



OBLONG. 



brevidens. Lea. 



heavier shell, and the nacre of all the specimens I have seen is more or less 

 purple, while that of parvus is always I believe white. Among many hun- 

 dred specimens which have come under my notice, I have never seen one of 

 any other colour. The texture of the nacre is also totally different, the latter 

 being more pearly than any other of our Uniones. In the epidermis and 

 beaks they also differ essentially. 



* On the authority of Ferussac. 



-\ The specimen of this species which I received from M. Cailliaud the 

 traveller is so much like JViloticns that I certainly would not myself have 

 separated it. 



