38 U.S. NATIONAL MUSEUM BULLETIN 292 



burrows, and at night some of the animals move to land at the water's 

 edge. 



While a number of usually epigean species occur in caves, only nine 

 of the West Indian decapods have become so completely adapted to 

 cave life that they probably are unable to exist elsewhere. Six of these 

 troglobites occur on Cuba, Typhlatya garciai, Troglocubanus calcis, 

 T. eigenmanni, T. gibarensis, T. inermis, and Procambarus niveus; one 

 on Mona Island and Barbuda, Typhlatya monae; and two on Jamaica, 

 Troglocubanus jamaicensis and Sesarma verleyi. The latter, insofar as 

 known, is restricted to a cave environment on Jamaica (Hartnoll, 

 1964, p. 164). It is "pale bluish white" in color, its integument is thin, 

 its legs longer than other West Indian species of the genus, and its 

 eyes are markedly reduced but pigmented. It was found by Hartnoll 

 "about 60 ft. below ground level [in] a slowly running stream with 

 areas of finely silted bottom . . . [and] under stones in a damp area 

 some distance from the water." In another cave he found this crab 

 in a "wide, slow-moving river with muddy banks and bottom . . . 

 [as weU as] on the banks." Although all of these animals occur in 

 caves, except for S. verleyi, details of their habitats have not been well 

 documented. 



Among the usuaUy epigean species reported from caves are Poti- 

 mirim mexicana, Macrobrachium carcinus, M. faustinum, Epilobocera 

 sinuatifrons , and Cardisoma guanhumi (see Nicholas, 1966) and 

 Sesarma bidentatum (see Hartnoll, 1964). Brother Nicholas found 

 these decapods in caves on Puerto Rico where he also collected 

 Xiphocaris elongata (in litt.). He has also indicated to us that Macro- 

 brachium carcinus at times of flood was reported to him to occur in 

 numbers in pools along Rio Camuy, presumably having been washed 

 out of underground passages connected \^dth Empalme Sinkliole. An 

 unidentified member of the genus Macrobrachium was collected along 

 with the troglobitic Typhlatya monae from a catchment basin on 

 Mona Island. 



Perhaps the most completely terrestrial decapod in the Antilles is 

 the hermit crab, Coenobita clypeatus, which ranges from sea level up to 

 1,300 feet on Dominica. Only one very small juvenile was found in 

 water during the period when observations were being made on that 

 island. Ocypode quadrata is largely confined to sandy beaches above 

 the high-tide line, but one juvenile specimen was collected almost 

 two miles from the coast along a freshwater stream on Dominica. 

 The most conspicuous element of the terrestrial decapod fauna during 

 most of the year is Cardisoma guanhumi. Thousands of these crabs 

 may be observed in the lower flood plains of rivers and in low-lying 

 land, apparently resting but alert, near the mouths of their burrows, 

 many, if not aU, of which penetrate the water table. After dark, 



