228 DR. H. GADOW ON MEXICAN [June 6, 



Isthmus to San Mateo del Mar near Tehuantepec. These lines 

 enclose all the most varied and characteristic physical features : 

 the highest mountains, part of the Central high plateau with 

 gradual slopes into the lowlands, abrupt boundaries, the hot low- 

 lands, the principal rivers, lakes, swamps, forests, and savannahs ; 

 Central or inland, Atlantic and Pacific climate. 



All the species, with available records, were sorted into six 

 groups : — Those which occur only in the cold and cool regions ; 

 those which are found in these and in the temperate zones ; in the 

 cool, temperate, and hot zones; temperate zone only; temperate and 

 hot ; ancl, lastly, hot or tropical only. 



Of course the lines of demarcation are quite arbitrary, but the 

 132 species collected by myself, represented by about 1000 

 specimens, with my knowledge of the country, gave me a lead. 

 Hot-lands extend from the sea-level to about 3000 feet, the 

 temperate zone to 5000 or 6000 according to the district. Every- 

 thing beyond 7000 feet can safely be considered within the cool 

 zone, and all stations above 9000 feet are decidedly cold. Lastly, 

 there is some safety in numbers. 



I. My own Collections : 131 species employed. 



No. of 

 Climate. species. Per cent 



1. Cold or cool only 22 17 ~1 



2. Cold and temperate... 6 5 }> within cool zone 38 sp.= 30 per cent. 



3. Cold to hot 13 10 J ^ 



4. Temperate only 12 9 [> within temperate zone 42 = 32 per cent. 



5. Temperate and hot ... 11 9 J "i within hot zone 91 = 70 per cent. 



6. Hotonly 67 51 3 (groups 6 + 5-1-3). 



131 101 



II. My own and previous Collections and records : 247 species, 

 then rounded up to 250. 



No. of 



Climate. species. Per cent. 



1. Cold or cool only 42 17 1 



2. Cold and temperate. . 20 8 ^within cool zone 86 sp.= 34 per cent. 

 8. Cold to hot 24 9-6J "1 



4. Temperate onlj^ 15 6 i> within temperate zone 99 = 40 per cent. 



5. Temperate and hot... 40 16 J ^ within hot zone 173 = 69 per cent. 



6. Hotonly 109 43-6 5 (groups 6 + 5 + 3). 



250 100-2 



These two calculations agree remarkably well : species restricted 

 to cool regions 17 per cent, in both cases; species occurring 

 within the cool regions 30 or 34 per cent, respectively ; and species 



