DECAPOD CRUSTACEANS OF THE WEST INDIES 23 



from the continent) . Once isolated in the Greater Antilles, it probably- 

 moved along the islands eastward to the Bahamas and southward 

 through the Lesser Antilles, reaching as far southwest as Curasao. It 

 seems odd that the islands closest to South America have not been 

 invaded by M. oljersii, and the obvious explanations are that either 

 M. faustinum arrived first, lessening the chance that its close relative 

 could become established even if it reached the islands, or that in 

 recent times the waterway between the mainland and the islands has 

 been a barrier to both species. 



The Astacidae: All of the West Indian members of this family are 

 endemic. Evidence that cambarine crayfishes lend themselves to 

 having been rafted from the Central American-Mexican area to the 

 Greater AntUles comes from several sources. Hobbs (1942b) in 

 discussing the habits of the crayfish Procambarus spiculifer (LeConte) 

 stated that "several times in removing dead limbs or logs from 

 streams in order to use a seine or dip net I have found females, carry- 

 ing young or eggs, wedged in a hollow limb or down in a crevice of 

 a log . . . ," indicating that crayfishes do frequent a potential raft. 

 Since then, other species have been observed in such microhabitats. 

 Faxon (1884), Hobbs (1942b), and Penn (1943, 1956) reported that 

 Cambarus uhleri Faxon, Procambarus pycnogonopodus Hobbs, and 

 Procambarus clarkii (Girard) invade brackish habitats (the latter 

 two, congeners of the Antillean crayfishes). Helff (1931) and Steeg 

 (1942) demonstrated that a few P. clarkii can survive up to 17 ppt 

 of NaCl for 7 days. Kendall and Schwartz (1964) also found that 

 other freshwater crayfishes, Cambarus b. bartonii (Fabricius) and 

 Orconectes virilis (Hagen), while intolerant of prolonged exposures 

 (600 hours) to salinities equivalent to that of sea water (about 30 

 ppt), a few individuals of both species lived longer than 500 hours. 



With the knowledge that crayfishes require only a high humidity 

 to keep their gUls moist for respiratory purposes, it would not be 

 necessary to assume that they needed to be submerged in salt water 

 at all; furthermore, were the raft (log) hollow, the crayfish therein 

 might well have moved above the water level during the overseas 

 voyage and remained there until the log had been lodged in an estuary 

 on Cuba or Isla de Finos, where the salinity was within the range 

 of tolerance of the emigrant. Even had it received numerous salt 

 water sprays, the gUl chamber might stUl have maintained a low 

 salt concentration. Thus, with the known proclivities of ovigerous 

 cra5rfishes for seeking shelter in hollow logs and their tolerance to 

 comparatively high concentrations of salt, it may be concluded that 

 the crayfish stock reached Cuba (Isla de Pinos) by fortuitous rafting. 



Probably the most primitive of the four crayfishes in the Antilles 

 is Procambarus atkinsoni, which occurs only on Isla de Pinos (see 



