ORTMANN : SOUTH AMERICAN NAIADES. 019 



58. Anodontites puelchana (D'()rbifj;ny) (1835). 



A^iodonta puelchana D'Orbigny, 1843, p. 620, PI. 79, figs. 7-9. 

 Glabaris paclchanus Simpson, 1900, p. 921. 

 Anoduutites puelchaiius Pilsbry, 1911, p. 609. 



Simpson (1914, p. 1420) unites this with ^4. Umnoica D'Orbigny, but the latter 

 has a very narrow prismatic border. According to my observations, the width 

 of this border is a very constant and important character. Simpson places this 

 species in the group of crispala; but there is not the sHghtest trace of the character- 

 istic sculpture of the epidermis of this group. That Simpson lias entirely mis- 

 understood this species is shown by the fact that he unites .4. obtusula Hupe with 

 it. The latter is a species which is not at all oblique. 



Type-locality. — Marsh of San Xavier on Rio Negro, above Carmen de Pata- 

 gones, Argentina. 



Additional Locality. — Twelve leagues from Chichinal, Patagonia (on Rio Negro) 



(Pilsbry). 



New Locality. — Rio Limay, Patagonia (drainage of Rio Negro) (W. Israel 



donor). Two specimens with soft parts, male and female. 



Distrihidion. — Known only. from the Rio Negro-drainage in Patagonia. Von 

 Ihering (1893, p. 118) lists it as from the lower Parana, but without substantiating 

 this record. 



According to D'Orbigny's description and figure, this species is an obliquely- 

 ovate, much compressed, thin shell, with shining epidermis, and wide prismatic 

 border. It is surely related to patagonica, being, however, not so high and more 

 elongated (height 57 to 65 pr. ct. of length, while patagonica has the height 60 to 

 84 pr. ct. The diameter is about 31 pr. ct. while in patagonica it never falls below 

 33 pr. ct. and only rarely below 40 pr. ct. 



The two specimens before me have the wide prismatic border, somewhat 

 unequal in width; the nacre is whitish with pinkish shades (D'Orbigny says "blanc- 

 rose"). The epidermis is highly polished and shining; there are some concentric 

 grooves, but the fine concentric strife are missing upon the greater part of the disk, 

 and are only slightly developed near the margins. There are, chieHy in my larger 

 specimen, a few scalariform stripes upon the anterior part of the shell, consisting 

 of radial bands of short, concentric wrinkles. Upon the posterior slope there is 

 an indication of a radial rib. Color of epidermis greenish brown, more greenish 

 toward the beaks, more brownish toward the margins, with very indistinct traces 

 of green rays upon the posterior slope. 



