22 U.S. NATIONAL MUSEUM BULLETIN 292 



The Palaemonidae : Twelve members of this family are found in 

 fresh waters of the West Indies. Among them are some of the most 

 unique of the endemic decapods, members of the troglobitic genus 

 Troglocubanus, which is represented on Cuba by four species and on 

 Jamaica by one. Their relationships to other members of the family 

 are at best remote, and, since all are cavernicolous, they should per- 

 haps be looked upon as relicts of a stock of the family that reached 

 the Antilles comparatively early, perhaps as early as the Miocene, 

 populating the freshwater systems of at least Cuba and Jamaica and 

 gaining access to the underground water systems on both. For some 

 reason the supposed epigean derivatives from the original stock were 

 unsuccessful and became extinct, leaving albinistic relicts as the only 

 evidence of their existence. Whether all six species represent inde- 

 pendent invasions of subterranean waters can be left only to con- 

 jecture, but a conclusion that there were at least two invasions, one 

 on each of the islands, seems inescapable. There is little likelihood 

 that a subterranean fresh water connection has ever occurred between 

 Jamaica and Cuba, and equally unlikely that any other type of 

 highway, along which they might have travelled after once having 

 become troglobitic, has ever joined the two islands. On the basis of 

 present information, we are unable to hazard a guess as to the area 

 from which the ancestral stock emigrated. For several reasons, how- 

 ever, it seems probable that the ancestors reached the islands in 

 pre-Pleistocene times. 



Of the five members of the genus, Troglocubanus eigenmanni 

 (provinces of Pinar del Rio and Matanzas) is probably the most 

 generalized, and the most specialized is T. inermis (Provincia de La 

 Habana). Closely related to the latter is T. gibarensis (Provincia de 

 Oriente). The Jamaican T. jamaicensis seems to have its closest 

 affinities with T. calcis (Provincia de La Habana). 



The endemic Macrobrachium faustinum appears to be the West 

 Indian counterpart of M. oljersii (Wiegmann), the range of which 

 extends from Mexico to Brazil and includes the Florida peninsula. 

 That the two have a recent common ancestry seems almost undebat- 

 able, and for the first half of the present centiu^y they were considered 

 to belong to a single species that was designated M. oljersii. One 

 must assume that the ancestral stock was a continental one, and a 

 postulate of its having reached the Greater Antilles from the Central 

 American-Mexican region rather than from South America seems 

 more probable for the reasons that the Greater Antilles are older 

 than the Lesser Antilles, and the stock would almost certainly be 

 more nearly isolated than if it moved northward along the islands 

 adjacent to the South American coast (it is now known to occur on 

 Curagao, Bonaire, and Tobago, which are only some 40 to 65 miles 



