DECAPOD CRUSTACEANS OF THE WEST INDIES 13 



127 (F7) Castle Bruce River, % mile above mouth, 30' (49, 73) 



128 (C6) Retaining wall of Kasiobna River at airport, 10' (73) 



129 (H3) Pool in abandoned bed of Belfast River, near mouth, 5' (35, 79) 



130 (HS) Boeri Lake, 2,850' (49) 



Distribution, Relationships, and Origins 



Wliile there were a number of insular masses in the Caribbean region 

 during the Cretaceous Period (Woodring, 1954, p. 724; see also Weye, 

 1966) — except for a chain of volcanic islands in the area now encom- 

 passed by the island of Cuba — most, if not all of the extant islands, 

 northern South America, and Central America were submerged. 

 Furthermore, there is no geological evidence for assuming the con- 

 tinuous existence of land masses anywhere in the Antilles prior to the 

 Eocene, and most of the islands are not known to be older than late 

 OUgocene or early Miocene; consequently, if this be true, the ances- 

 tors of the present freshwater and terrestrial faunas on them could not 

 have been permanently established earher. 



Since about the turn of the present century, a number of students 

 of zoogeography (among them Ortmann, 1905; Barbour, 1914; Villa- 

 lobos, 1955; Rivas, 1958; and, more recently, Hobbs and Villalobos, 

 1964) have postulated one or more land bridges between the Central 

 American-Mexican region and the Greater Antilles over which various 

 faunal elements might have reached the islands. Some have advocated 

 another such bridge that connected the Lesser Antilles with northern 

 South America. 



Other zoogeographers (including Matthews, 1915 and 1939; Myers, 

 1938; DarUngton, 1938 and 1957; Simpson, 1956; and Rosen and 

 Bailey, 1963) have presented convincing arguments against the exist- 

 ence of such bridges. Instead, they have proposed that the Antillean 

 faunas were derived from waifs or strays that reached the islands 

 accidentally. Recently, Hobbs (1967) has admitted that, in hght of 

 data involving the tolerance of cambarine crayfishes to much higher 

 salinities than formerly had been assumed possible, the necessity for 

 a land bridge seems far less real. 



The majority of the Antillean freshwater and terrestrial decapods 

 are kno^vn either to be tolerant of sahnities equivalent to that of sea 

 water — many actually invading the ocean — or to have larval stages 

 that typically occur in the sea. For some of these decapods, few data 

 are available, and, in the absence of a fossil record, neither the time of 

 arrival of then ancestors in the islands nor the routes taken by them 

 can be postulated with any degree of certaintj^ 



In contrast, there are a number of species that are typically fresh- 

 water inhabitants with no obviously closely related marine ancestors 

 and that complete their life cycles in or near fresh water. For at least 



