514 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 91 



most is longest and most slender; anterior internal lobes of carpus 

 armed with a single, well-developed, smooth, clean-cut, spine; all 

 carpal spines with acute corneous tips. Upper longitudinal margin 

 of merus with a series of sharp corneous spines, of which the anterior- 

 most is the larger and elevated on a small conical tubercle above the 

 level of the rest; anterior margin of merus in front of this anterior 

 spine has a very slightly marked, minutely denticulate lobe; a few 

 other tiny denticles may also occur along the anterior margin of the 

 merus. Inner margin of ventral surface of ischium with low, broadly 

 conical, corneous scale-tipped tubercle at anterior end and a relatively 

 insignificant, low, nodular swelling at posterior end, margin of ischium 

 between these two low elevations virtually straight, at most only very 

 slightly sinuous. 



vv 



O — o 



Figure 64. — Aegla riolimayana, new species, male holotype: a. Dorsal view; h, lateral view 

 of anterior portion; c, sternum of third and fourth thoracic somites; d, inner ventral margin 

 of ischium of left cheliped; e, lateral view of second abdominal epimeron. a, b, natural 

 size; c-e, twice natural size. 



Anterior dorsal angle of epimeron of second (in lateral view, ap- 

 parent first) abdominal somite produced to form an acute corneous 

 tipped spine ; anterior margin below this spine more or less straight. 



Holotype. — The largest of five males taken by John W. Titcomb, 

 November 19, 1903, in the Rio Limay, which forms the boundary line 

 between the territories of Rio Negro and Neuquen, Argentina. These 

 specimens were taken not far from the outlet of Lago Nahuel Huapi, 

 where Mr. Titcomb had obtained other specimens of this species a 

 few days before. The holotype, U.S.N.M. No. 80025, measures 

 23.5 mm. in length of carapace and rostrum together. 



