LITTORAL FAUNA OF THE PANAMA PROVINCE. 235 



tilde, with its accompanying low temperature, exerts in extending the south- 

 ern limit of a northern fauna. 



The western coast of Central America and Mexico from Panama to 

 Guajmas — the region explored by the "Albatross" in 1891 — forms a 

 small part — the so-called Panama Province — of the great Tropical carcino- 

 logical Kealm. The immediate origin and special relations of this fauna 

 remain to be considered. 



As soon as the shore Crustacea of the Panama Province came to be 

 known with any degree of fulness, chiefly through the publications of 

 William Stimpson, it appeared that they belonged, with few exceptions, to 

 genera living on the Atlantic side of the continent, in the Gulf of Mexico 

 and the Caribbean Sea. It also appeared that although but few identical 

 species inhabited the two coasts,* yet a very lai'ge number of the Panamian 

 species were represented by corresponding, closely related species in the 

 Caribbean Sea. In many cases these " representative " species on the two 

 sides of the continent are barely distinguishable, and, were it not for the 

 continental barrier separating the seas inhabited by them, they would be 

 deemed but varieties or geographical races of one species. 



I have brought together in the following list some of the similar littoral 

 species of the Panamian and Caribbean Provinces. Cosmopolitan species are 

 of course omitted. t 



Pacific Coast. Atlantic Coast. 



Leptopodia debilis. Leptopodia sagittaria. 



Podochela vestita. Podochela riisei. 



Anasimus rostratus. Anasimus fugax. 



Collodes granosus. ) ^ ,,■,.. • 



° . ^ . S- Collodes trispmosus. 



" tenuirostris. y 



Batrachonotus nicholsi. Batrachonotus fragosus. 



Euprogiiatha granulata. Euprognatha rastellifera. 



Sphenocarcinus agassizi. Sphenocarciuus corrosus. 



Epialtus sulcirostris. Epialtus affinis. 



Tyche lamellifrons. Tyche emarginata. - 



« Tlie following Decapods, in addition to certain species of world-wide range, have been recorded from 

 the Panamian and West Indian sides : 



Microphri/s weddnllii, Acanthonyx petiverii, Carcimis mams, Cronius ruber, Achelous spinimanus, Gelasi- 

 mus niaracoaiii, G. heterochdes, 0. vocator, G. stenodactijlus, Geor/rapsus lieidiis, Oci/pode arenaria, Ariitus 

 pisoni, Goniopsis cruentata, Hippa emerita, Petrolisthes armalm, Alpheus minor, A. heterocheles. The species 

 of Gelasimvs and Alpheus are given on Kingsley's authority. Botli of these genera need careful revision. 



t A few species are included which are not very closely related, but which arc the only species of the genus 

 known, e. g., the two species of Sphenocareiiius. Such cases point in the same direction as the rest, i. e. to the 

 West Indian origin of the Panamian littoral fauna. 



