Narrati\'e of Bahama I^^ximcdition. 209 



crustacean fauii;c on the two sides of the (iulf Stream than 

 exists between the fauna? at a depth of eighty to two hun- 

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

 large to justify dogmatic generalizations, but they are never- 

 theless signiiicant. being borne out, moreover, b^• a comparison 

 •of series of invertebrates belonging to ether groups. The 

 Dry 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 that there must be 

 some method by which Crustacea and other groups of inverte- 

 brates 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 winds 

 would perhaps be borne across the Gulf Stream before the 

 Bahamas were passed. Whether the eggs have any con- 

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

 but if ,they have, it seems likeh 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. 

 E-pialtns hituhcrciilatiis M. E. is represented by a minute speci- 

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

 Acaiit/wnyx ■pctiverii 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 chela?. 

 The rostrum itself is produced forward into a pair of flattened 

 and expanded teeth, J\Iit/u'ax spiiiosissiimts ( 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 



