66 U.S. NATIONAL MUSEUM BULLETIN 292 



proximally, dark green distally with patches of brownish pigment 

 alternating with aqua spots in distal portions of both rami; marginal 

 setae golden. Telson Hght green anteriorly, dark green posteriorly 

 with brownish spots and brown tip. 



Brown Phase: Pattern essentially identical; colors, however, range 

 from cream through pale buff to dark brown. 



Material examined. — The Dominican collections contain only 15 

 males (carapace lengths 11.0-31.0 mm) and 4 females (cl 12. 0-17. 1mm), 

 1 of which (cl 17.1 mm) bears eggs. 



Ecological notes. — Atya scabra is decidedly less common on 

 Dominica and is much more restricted in its habitat distribution than 

 is A. innocous. Insofar as our collections indicate, A. scabra frequents 

 the cascading reaches and riffles of small streams at elevations of 50 

 to 350 feet, where it secretes itself among the stones over and among 

 which water is rusliing. Although it must travel through pools in 

 moving from one congenial niche to another, it was neither observed 

 nor collected in a pool during this study. The only specimens obtained 

 were caught by placing a net in the cascading waters and moving the 

 larger stones immediately upstream so that the swift current washed 

 the shrimp sheltered under and among the rocks into the net. 



Distribution. — Mexico and the West Indies to Estado de Per- 

 nambuco, Brazil (Cuba, Jamaica, Hispaniola, Puerto Rico, Dominica, 

 Truiidad). 



Dominica Stations: 1, 2, 4, 50, 66, 74 (50-350 ft.). 



Remarks. — The differences between this species and A. innocous 

 are discussed under the latter species (p. 61). 



We agree with Holthuis (1966) that A. scabra is probably confined 

 to eastern America, but A. rivalis Smith, 1871, from the Pacific drain- 

 age of the Americas has an almost identical color pattern; the minor 

 morphological characters by which that species is distinguished may 

 prove eventually to be of no more than subspecific importance. 



The single ovigerous female of A. innocous from Dominica was 

 collected on January 29. 



Genus Jonga 



9. Jonga serrei (Bouvier) 



Figures 11, 14/, g 



Orlmannia Serrei Bouvier, 1909, p. 332 [type-locality: vicinity of Havana, Cuba]; 



1925, p. 279, figs. 645-654. 

 Orlmannia serrei. — Schmitt, 1935, p. 137. 

 Potimirim serrei. — Holthuis, 1951, p. 3 [by implication]. 

 Jonga serrei. — Hart, 1961a, p. 3, figs. 1-2. 



Diagnosis. — Orbital margin armed dorsally with row of denticles. 

 Rostrum without dorsal teeth, ventral margin dentate but not finely 



