DECAPOD CRUSTACEANS OF THE WEST INDIES 109 



bands on proximal podomeres becoming red at distal end of merus; 

 bands on carpus and propodus slate blue. Pleopods translucent pale 

 pinkish blue. 



Material examined. — The Dominican collections contain 72 males 

 (carapace lengths 6.8-33.3 mm), 49 females (cl 5.2-24.0 mm), in- 

 cluding 9 mth eggs (cl 10.0-24.0 mm), and 4 juveniles (cl 3.1-4.2 

 mm). None of the males has the appendix masculina on the second 

 pleopod rudimentary, and a carapace length of 5 mm was, therefore, 

 rather arbitrarily chosen as the size separating juveniles from sexually 

 recognizable individuals. 



Ecological notes. — Both the adults and young of this species 

 appear to be restricted to riffle areas and low cascades that are shared 

 with the local species of Atya. Perhaps its absence in some of the 

 streams at higher elevations (above 2,500 feet) is due to the lack of 

 water except during rainy periods. It seems higlily improbable that 

 a member of this species, with its ungainly major cheliped, could 

 construct any kind of burrow in which it might seclude itself should 

 the riffle become dry. This shrimp is a rapid swimmer, speeding either 

 up or downstream with considerable grace. Even though much more 

 widespread along the stream gradients (frequenting almost all riffles) 

 than any of the shrimps on Dominica except the two species of Atya, 

 it apparently is as limited ecologically as are those (M. acanthurus 

 and Jonga serrei) that seem to be restricted to the lowermost portions 

 of streams. 



Distribution. — Estado de Puebla, Mexico, to Estado de Sao 

 Paulo, Brazil (Jamaica, Hispaniola, Puerto Kico, Guadeloupe, 

 Dominica, Saint Vincent, Grenada). 



Dominica Stations: 1-5, 7, 8, 11-13, 19, 21, 22, 24, 26, 29, 30, 32, 

 33, 35, 42-45, 47, 48, 52, 55, 56, 63, 66, 69, 71, 73-78, 80, 84, 87, 88, 

 101, 105, 109 (0-2,500 ft.). 



Remarks. — The Dominican collections are not sufficiently large 

 to furnish reliable information on the presence of a breeding season 

 in this species. Ovigerous females were found in February, March, 

 July, and November, but it may be significant that none of the six 

 females with a carapace length of more than 10 mm taken in January 

 bore eggs, and only 1 of 15 had eggs in February, whereas 6 of the 

 15 collected in March were ovigerous. 



22. Macrobrachium jelskii (Miers) 

 Figure 25/ 



Palaemon jelskii Miers, 1877, p. 661, pi. 67: fig. 1 [type-locality: Saint-Georges 



(Oyapock), French Guiana]. 

 Bithynis jelskii. — Young, 1900, p. 489. 

 Macrobrachium amazonicus. — Schmitt, 1936, p. 373 [not Palaemon amazonicus 



Heller, 1862]. 



