Narrative of Bahama Expedition. 209 



crustacean fauna^ on the two sides of the Gulf Stream than 

 •exists between the faunrc at a depth of eighty to tw'o hun- 

 dred and fifty fathoms. Our series of forms is not sufficiently 

 large to justify dogmatic generalizations, but they are never- 

 theless significant, being borne out. moreover, by a comparison 

 of series of invertebrates belonging to other groups. The 

 Drv Tortugas are about three hundred and eighty miles from 

 Spanish Wells, while the Pourtales Plateau is only about 

 eighty miles from Havana. The Gulf Stream interposes the 

 same barrier in both cases. Without discussing the question 

 of a previous land connection, it seems thiit there must be 

 some method by which Crustacea and other groups of in\'erte- 

 hrates are distributed in a manner practically independent 

 ■of the current or depth of the Gulf Stream. Many crus- 

 tacean larva? are pelagic, and are probably transported long 

 distances by the more superficial currents. A larva starting 

 at the Tortugas during the prevalence of northerly wunds 

 would perhaps be borne across the Gulf Stream before the 

 13ahamas were passed. Whether the eggs have any con- 

 siderable power to withstand dessication or not I do not know, 

 but if thev have, it seems likel} that they would often be 

 transported on the feet of water-birds. 



All of the six: crustaceans that we found near Eleuthera 

 which have not hitherto been mentioned, are brachyuran crabs. 

 Epialtiis hiluhcrcuhittis M. E. is represented by a minute speci- 

 men with a veiy broad rostrum ending in two blunt points. 

 Acanthonyx ■petirerii M. E. has the distal portion of each of 

 the walking legs expanded into a lamella which apposes the 

 hook-like dactylopodite so that a pseudochela is formed for 

 prehension. The carapace suddenly narrows back of the eyes, 

 and a number of hair-like cirrhi are borne above the rostrum 

 and in bristle-like bunches on the inner sides of the chehe. 

 The rostrum itself is produced forward into a pair of flattened 

 and expanded teeth. Mithrax spiiiosissinnts ( Lamk.) is a very 

 large, dark red spider-crab, with a spread of legs of twenty- 

 one inches, and is characterized by having a row of smooth 

 round knobs on the upper edge of the hand. The carapace 



