No. 497] BERMUDIAN DECAPOD FAUNA 



293 



I'uchggnipsus t rmisvcrsus. Domecia hispida. 



Planes minutus. Petrolisthes armatus. 



Nearly all the widely distributed species, included in 

 the last list, are found on the West Coast of Africa. But 

 some additional species, common to Bermuda and the 

 West Indies, are also found on the West African coast. 

 Namely : 



Goniopsis cruentatus. Calappa marmorata. 



Callinectes marginatus ? larvatus. C. gallus, galloides. 



Aside from the widely distributed grapsoid crabs, 

 found in all tropical seas, very few of the Bermuda 

 species are found on the Pacific coasts of Central and 

 North America. But some others are represented there 

 by closely allied species or subspecies. The species that 

 have been considered identical by recent good authorities 

 are as follows : 

 Goniopsis cruentatus. * Domecia hispida. 



* Grapsus grapsus. Epialtus bituberculatus (varie- 



* Geograpsus lividus. ties). 



* Pach !,,,,■(( p.sus trans versus. * Calappa gallus (varieties). 



Those preceded by an asterisk are circumtropical. 



It is well known that a considerable number of species 

 of Mollusca, Echinoderms, Anthozoa, etc., as well as 

 Crustacea, are common to West Africa, Brazil and the 

 West Indies. Such species may have originated on 

 the African coast and thence migrated across the At- 

 lantic to South America, and thence northward to the 

 West Indies, Florida and Bermuda, during recent geo- 

 logical times. All the species of Decapod Crustacea 

 having this wide range exist for a considerable length of 

 time as free-swimming larval forms, in the zoea and 

 megalops stages. These larval forms may be carried 

 long distances by the prevailing oceanic currents, espe- 

 cially in the regions of the trade winds. 



It is scarcely admissible to suppose that they could have 



