LITTORAL FAUNA OF THE PANAMA PROVINCE. 235 
tude, 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 
Guaymas— the region explored by the “Albatross” in 1891—forms a 
small part — the so-called Panama Province — of the great Tropical carcino- 
logical Realm. 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 large 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.f 
Pactric Coast. ATLANTIC Coast. 
Leptopodia debilis. Leptopodia sagittaria. 
Podochela vestita. Podochela riisei. 
Anasimus rostratus. Anasimus fugax. 
l re : ele 
See Sena ‘ Collodes trispinosus. 
oo tenuirostris. 
Batrachonotus nicholsi. Batrachonotus fragosus. 
Euprognatha granulata. Euprognatha rastellifera. 
Sphenocarcinus agassizi. Sphenocarcinus corrosus. 
Epialtus sulcirostris. Epialtus affinis. 
Tyche lamellifrons. Tyche emarginata. 
* The following Decapods, in addition to certain species of world-wide range, have been recorded from 
the Panamian and West Indian sides : 
Microphrys weddellii, Acanthonyx petiverii, Carcinus menas, Cronius ruber, Achelous spinimanus, Gelasi- 
mus maracoani, G. heterocheles, G. vocator, G. stenodactylus, Geograpsus lividus, Ocypode arenaria, Aratus 
pisoni, Goniopsis cruentata, Hippa emerita, Petrolisthes armatus, Alpheus minor, A. heterocheles. The species 
of Gelasimus and Alpheus ave given on Kingsley’s authority. Both of these genera need careful revision. 
+ A few species are included which are not very closely related, but which are the only species of the genus 
known, e. g-, the two species of Sphenocarcinus. Such cases point in the same direction as the rest, ¢. e. to the 
West Indian origin of the Panamian littoral fauna. 
