ZOOGEOGRAPHY 363 



typically exasperating example — there is no doubt that other hamoti are living 

 on the Antillean chain — we simply do not know enough. 



Countless examples could be cited but many of these have been already 

 stated in the preceding pages, and need not be restated here. There are numer- 

 ous genera which appear to have moved up the Central American route 

 {Eurhexius), others to have used the Antillean route, others both routes. 



In the examples of genera using the Mexican route, they nearly always 

 dwindle or stop at the northern limit of the rain forest and therefore aid in 

 delimiting the Neotropical Region. My data show this limit to be just south 

 of the Tropic of Cancer on the Atlantic side (southern Tamaulipas — northern 

 Vera Cruz), as the description of new species attest. In so far as these data go, 

 they confirm the work of Smith (1940) on the zoogeography of Mexico, 

 especially with respect to the lizard genus, Sceloporus. 



The northward extent on the Pacific side is unknown. 



Thus, to sum up this first aspect, a major problem for the future is to 

 ascertain the relative usage of the Antillean versus the Mexican highway be- 

 tween the Nearctic and Neotropical Regions. Emerging as subproblems are 

 the (1) extent of neotropical species on the Pacific side of Mexico; (2) the 

 ratio of nearctic to neotropical elements in the southern third of peninsular 

 Florida; (3) the ratio of Central American to South American elements at 

 several points through Central America, especially the shift between Panama 

 and Guatemala. This requires much expeditionary work, followed by difiicult 

 taxonomic research. The regions in which materials are critically needed appear 

 to be two: the Antilles as a whole; and the Pacific slope of Mexico, especially 

 from Mazatlan to Manzanillo. 



It must be pointed out that two influences may obscure the relationships 

 present. These are chiefly intra-tropical. The first of these is altitude. Most of 

 the vast neotropical area lies below 3000 feet, but the species may penetrate at 

 different latitudes to different elevations, following the well known relationship 

 between altitude, climate and biome from pole to equator. We have no informa- 

 tion on this point either, at least nothing comparable to Schmidt's study of 

 vertical distribution of the salamanders of the genus Oedipus in Guatemala 

 (1936). We know that pselaphids can penetrate to moderately high altitudes: 



Table V 

 SELECTED ALTITUDE RECORDS OF PSELAPHIDAE 



Species Elevation Country Source 



in feet 



Hamotus setipes 800- 1500 Bugaba, Panama Sharp, 1887 



2000- 4000 Chiriqui, Panama Sharp 



Metopias elegans 3000- 4000 Chiriqui, Panama Sharp 



Arthmius armatellus 2000- 4000 Chiriqui, Panama Sharp 



Oxarthrius hamaticollis 3000 Las Mercedes, Guatemala Sharp 



Batoctenus simplex 2000- 4000 Chiriqui, Panama Sharp 



Batoctenus puncticollis 2000- 4000 Chiriqui, Panama Sharp 



Euphalepsus centralis 7000- 9000 San Geronimo, Guatemala Sharp 



Euphalepsus reitteri 2500- 4000 Chiriqui, Panama Sharp 



