A NEW PEAHLY FRESHWATER MUSSEL OF THE GENUS 

 HYRIA FROM BRAZIL. 



By L. S. Frierson, 



Of Frier son, Louisiana. 



Wliile looking over the Lea collection in the United States National 

 Museum the shell to be described below was noted, the label attached 

 to it being " Eyria corrugata, from the Amazon River, Brazil, from 

 Captain Brown." It differs so much from that species indeed as to 

 be only placed in Hyria on account of the radial beak sculpture, and 

 epidermis. The shell resembles, perhaps, the Prisodon hrownianus 

 Lea more than it does the ordinary Hyrias, but that shell is smooth, 

 and the teeth differ considerably. The shell is decidedly novel, and 

 really appears to be a connecting link between the genera Hyria and 

 Diplodon. (It is not impossible that this species may be the " Hyria 

 Tiumilis Troschel," unpublished so far as I am aware, a species said 

 to be from Guiana, and referred to by Wiegmann in 1847, the name 

 being suggestive.) 



HYRIA AMAZONIA, new species. 

 Plate 12. 

 Shell small, sohd, triangular, inflated. Length, 4; height, 2.7; 

 diameter, 2 cm., narrow in front, and almost square with the base, 

 which is straight almost to the posterior end, where there is a hint at 

 a sulcus. The dorsum is nearly straight, rising into a slight wing, 

 which in the type-specimen is just behind the middle. The posterior 

 end descends rapidly to the rounded posterior point. The beaks are 

 heavily radiately corrugated, breaking up in the center of the shell 

 into pustulations, and becoming smooth next to the margin. Epi- 

 dermis dull reddish brown, without other markings. The cavity of 

 the shell is tray shaped, beak cavities very shallow. In the left valve 

 there are two laterals, short, and remote from the cardinals, of which 

 there is one low, compressed, and nearly vertical, in front, and a hint 

 of another just beneath the beak. In the right valve there is one 

 lateral and one low ragged split-up cardinal. The protractor-pedis 

 scar is either absent or placed above the adductor scar, and is very 

 small, confluent behind. Nacre white and purplish (somewhat dis- 

 eased in the center of the type-specimen) . 

 Type.— Csit. No. 83877, U.S.N.M. 



Proceedings U. S. National Museum, Vol. 47— No. 2053. 



