DECAPOD CRUSTACEANS OF THE WEST INDIES 209 



ings and green patch on side opposing merus; both fingers white. Small 

 chela mostly straw colored; merus with longitudinal chocolate stripe; 

 fingers and lateral three-fourths of palm pinkish cream. 



Second through fourth periopods straw with dark brown spots and 

 bands above and gray below; dactyls pinkish tan. Merus of second and 

 third pereiopods with one or two distal white spots, that of fourth with 

 distal white band and one or two spots, that of fifth with three trans- 

 verse white bands; carpus of second and third pereiopods dark brown 

 above, straw laterally, that of fourth and fifth dark proximally and 

 lighter distally, each with light spot; propodus of all legs with dark 

 brown and white spots. 



Sternum gray; abdomen tan to brown with lighter median stripe. 



There is considerable variation in the coloration and pattern in 

 this crab but the basic patterns described above are evident in most, 

 except in those that apparently have not molted for a long time. 



Material examined. — The Dominican collections contain 59 

 males (carapace lengths 4.2-11.0 mm) and 22 females (cl 6.0-12.4 

 mm), including 3 with eggs (cl 6.8-8.2 mm). 



Ecological notes. — Nowhere on Dominica were fiddler crabs 

 found to be abundant except in the large mudflat south of the Indian 

 River at Portsmouth (pi. 4a). Here two of the species, Uca burgersi 

 and U. vocator, can be numbered by the thousands, and it was here also 

 that the single specimen of a possible third species referred to below 

 was found. In an area bounded by Pterocarpus and coconuts with 

 dense growths of the arum Montrichardia arborescens and clumps of 

 the fern Acrostichum daneaefolium, these crabs abound, along with 

 Ucides cordatus, Goniopsis cruentata, and occasional individuals of 

 Callinectes bocourti. The area has no direct connection with the Carib- 

 bean and probably receives salt water only during exceptionally high 

 tides. The so-caUed mud flat might better be described as a large 

 grassy marsh with the water table practically at the surface and A\dth 

 a deep deposit of organic debris. The soil is soft and can be dug readily 

 without the aid of a tool. Within 25 feet from the shore one becomes 

 mired in mud to a depth of almost two feet. 



In some portions of the marsh, burrows of fiddler crabs were so 

 close together that a person could scarcely avoid covering one or 

 two entrances with each step. Along the western shore of the marsh, 

 in a small area not yet invaded by Montrichardia, there were between 

 60 and 100 burrows per 100 square feet. In this area, the ground was 

 so soft and so riddled with burrows that each step of the observer 

 resulted in a coUapse of several tunnels and a scurrying of the crabs 

 from their mouths. 



The burrows of the females were consistently without chimneys; 

 however, those of the males of Uca vocator were marked by neat 



