196 U.S. NATIONAL MUSEUM BULLETIN 292 



Crabs of intermediate size are the most colorful, as follows: 



Central portion of carapace brownish pnrple with greenish-yellow 

 transverse band posterior to frontal region and with scarlet front. 

 Lateral border of branchial region cream with purple blusli changing 

 posteriorly to orange and to pink on intestinal region. Lateral wall of 

 carapace white with pink blush posteriorly. Orbital, gastric, and mesial 

 portions of branchial regions showing cream spots. Eyestalks reddish 

 orange above, cream below. Third maxOlipeds cream. 



Basal podomeres of cheliped cream; merus orange buff, carpus 

 cream with i)urple blush, and chela mostly cream except for diffuse 

 reddish purple on flexor surface of palm and at base of movable 

 finger. Tips of fingers corneous (tan). 



Second through fifth pereiopods progressively less brightly colored 

 on extensor margins; second pereiopod pale pinkish gray; coxae of 

 remaining pereiopods pale pink; distal podomeres, except dactyl, 

 bright pinkish orange; dactyl yellow. 



Sternum and abdomen cream, latter with pink blush on anterior 

 somites. 



Material examined. — The Dominican collections contain 28 

 males (carapace lengths 6.2-89.7 mm), 15 females (cl 8.0-63.3 mm), 

 and 2 juveniles (cl 3.8-5.0 mm). Barely discernible vestigial first 

 pleopods are present in the smallest male. 



Ecological notes. — Cardisoma guanhumi is perhaps the crab most 

 often seen on Dominica. In almost any of the low-lying coastal areas, 

 hundreds of the pink or orange juveniles maj^ be seen during the day 

 near the mouths of their burrows. Apparently during the day they 

 seldom wander more than a few feet away from their burrows, and 

 most were observed less than a foot away. They usually can be ap- 

 proached to \\'ithin a distance of 15-20 feet and occasionally as close 

 as 10 feet, but, if the observer moves closer, the crabs make a speedy 

 retreat into their holes. Only once were two crabs seen to disappear 

 into the same excavation. The burrows of these pinkish-colored crabs 

 are constructed among those of the bluish or white members of the 

 same species; inasmuch as the adults are apparently all white or 

 bluish, presumably the lighter colored ones are older individuals. 



The adults, although less frequently seen, are apparently as gre- 

 garious as are the young. In a poorly drained coconut and banana 

 plantation near the mouth of the Layou River, holes almost a foot in 

 diameter are not uncommon, although the majority of them are half 

 that size. At times, these large crabs climb to the mouths of their 

 burrows, where they remain motionless for long periods of time. If a 

 person approaches such a crab, it retreats below the surface but often 

 stops above the water table; a closer approach, however, causes the 

 crab to plunge quickly into the water. A few individuals were caught 



