440 



Annals of the Carnegie Museum. 



granulated, almost smooth on proximal parts of outer and inner side, 

 with a small spine near distal end above. Lower side with two rows 

 of spiniform granulations, most distinct in young individuals. Ischi- 

 opodite of the third pah' of pereiopods with a strong hook. Copiilatory 

 organs (first pair of abdominal appendages) short and straight, with a 

 prominent shoulder on the anterior margin near 

 the tip. Outer and inner j)art in close apposition 

 to their tips ; outer part ending bluntly, the inner 

 slightly longer and thinner, but also blunt. The 

 inner part carries, at its anterior side, not far from 

 the shoulder, a small, procurved, horny spine. 

 Inner face of inner part tlattened, and slightly 

 dilated, with two rows of bristles, which diverge 

 from a low, oblique median rib. 



Tlie male of the second form differs in the less 



distinctly granulated carapace ; the chehe are 



.^--''''T'^^-^ weaker; the hooks of the third pereiopods smaller; 



^ — the copulatory organs are similar, but the horny, 



Fig. I. Male copu- procurved spine is replaced by a blunt tubercle 



latory organ of right that is not horny. (This gives the whole organ 



three blunt tips. ) 



Female: Similar to the male of the second form. 

 A)injilits ventralis transversely rhomboid, forming 

 a simple tuberculiform elevation, with an S-shaped 

 longitudinal fissure, but without any depressions. 

 Locality : Los Amates, Province of Izabal, Gua- 

 temala. In small streams and swales. January 

 20, 1905; collected by E. B. ^Villiamson, of Bluffton, Ind. (About 

 4 to 5 miles due south of the town of Izabal, south of Rio Malagua.) 

 There are 27 specimens in the lot, 13 (^ , 14 9- Only one (the 

 largest) is a male of the first form. Most of the specimens are very 

 young. 



The measurements of the largest (j^ (I) and O are as follows: 

 (^ . Total length 51.5 mm., carapace. 25 mm., anterior section of 

 carapace 16.5 mm., areola 8.5 mm., width of areola in the middle 

 0.5 mm., abdomen 26.5 mm., length of hand 20 mm., of palm 11 

 mm., of fingers 9 mm. 



9- Total length 49.5 mm., carapace 24.5 mm., anterior section of 

 carapace 16 mm., areola 8.5 mm., width of areola in the middle 0.5 



side seen from outside. 

 Fig. 2. Male copula- 

 tory organ of right side 

 seen from inside. Fig. 

 3 . Annulus ventralis 

 of female. All figures 

 enlarged twelve diam- 

 eters. 



