488 MEMOIRS OF THE CARNEGIE MUSEUM. 



Kuestcr, atratus Sowerby, oblasati D'Orbigny, chUuemis Kuester, aureus Simpson. 

 But the differential characters of these are very obscure, and I should not be as- 

 tonished if some of these names should prove to be synonyms. 



Similar forms are known from the eastern foot of the Cordilleras in Patagonia, 

 in the drainage of the Rio Negro. Of these the following material is at hand: 



6. DiPLODON PATAGONicus (D'Orbigny) (1835). 



Unio patagonicus D'Orbigny, 1843, p. 610, PI. 70, figs. 1-4. 



Diplodon patagonicus Simpson, 1900, p. 885; 1914, p. 1275; Pilsbry, 1911, p. 610.'* 



Type-locality. — Rio Negro, 10-12 miles above its mouth. 



New Locality. — Rio Limay, Patagonia (Received in exchange from W. Israel), 

 one right valve. 



Distribution. — Rio Negro and its tributary Rio Limay in Patagonia. 



The specimen at hand is very poor, with the epidermis worn off, but it is un- 

 doubtedly this species, which is characterized by its elongated outline and a shallow 

 radial groove upon the posterior slope. 



This species is not at all related to D. parallelopipedon (Lea), with which 

 it has been associated by Simpson. It has, indeed, a similar elongated outline, 

 but the characteristic strong and elevated posterior ridge of the latter species is 

 entirely absent. 



7. Diplodon frenzeli (Von Ihering) (1893). 



Unio frenzelii Von Ihering, 1893, p. HI, PL 4, fig. 12. 



Diplodon huapensis Bartsch, 1906, p. 394, PI. 27, fig. 1; PL 28, fig. 1; PL 29, fig. 2. 



Diplodon frenzeli and huapensis, Simpson, 1914, pp. 1264, 1265. 



Type-locality. — Patagonia. 



Other Localities. — Patagonia, foot of the Cordilleras (Von Ihering); small 

 lake on Victoria Island in Lake Nahuel Huapi, Argentina (Bartsch, huapensis). 



Locality Represented in Carnegie Museum. — Lake Nahuel Huapi, Argentina 

 (C. H. Eigenmann coll., 1919). One gravid female with soft parts. 



Distribution. — Known from Patagonia, at the foot of the Cordilleras in the 

 region of Lake Nahuel Huapi (Rio Negro drainage). The locality "Chile" given 

 by Von Ihering is rather vague; and "Os Perus, Sao Paulo, Brazil," given by 

 Simpson for frenzeli is probably incorrect. 



My material is too poor to give a full account of this species, but I am sure 

 that my only specimen belongs here, and I also believe that huapensis is the same. 



" Unio patagonicus Reeve, XVI, 1865, PI. 21, fig. 93, is not this. 



