34 



SYNOPSIS OF 



WIDE. 



Myt. Nilolicus. ^oorf. 

 Le jTiutel. Man. 

 Iiid. muten Rang. 



*elongata. Lea. 



Irid. elongata. Sow. 



*soleniformis. Lea. 



Mycetopodaf soleniformis. D'Orb. 



WIDE. 



*siliquosa. Lea. 



An. siliquosus. iSpia;. 



An. pygrncELim (young). Spix 



An. Ion gin us. Spix, 



Irid. longina. Per. 



Mycetopoda siliquosus. D^Orb. 



*coelestis. Lea. 



Irid. rostrata ? Rang. 



t In the present arrangement, founded on the form of the hinge, I have deemed it better not to adopt D'Orbigny's 

 genus Mycetopoda, founded on the natural character or habit of the animal. He says, " perforat, sicut pholadae." 

 In this habit it resembles U7iio oriens (nobis), which I have elsewhere stated buries itself about twelve inches 

 below the surface of the sand in which it lives. D'Orbigny mentions that the two anterior cicatrices are widely 

 separated. A more important character appears to be in the fact, that the smaller cicatrix is placed before the 

 larger one. In the Unio and Anodonta it is placed below it, and in the Hyria (Lam.) it is placed above, that 

 is, in a line with the beak. I regret that I have only the very short description that this distinguished na- 

 turalist and traveller has given in his Synopsis. Should he publish these descriptions in a fuller manner, 

 which I believe he intends, we may be so informed as not to disagree with him. 



