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; and, 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. Hvery- 
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 i) 
2. Cold and temperate... 6 5 within cool zone 38 sp.= 30 per cent. 
3. Cold to hot ............ 13 10 
4, Temperate only ...... 12 9 pub temperate zone 42 = 32 per cent. 
5. Temperate and hot... 11 Sh ie) pe hot zone 91 = 70 per cent. 
G EGE Olly sorarosseonaane OW 51 (groups 6+5+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 oniy...... 42 iy 
2. Cold and temperate... 20 8 within cool zone 86 sp.= 84 per cent. 
3. Cold to hot ........... 24 96 J 
4. Temperate only ...... 15 6 within temperate zone 99 = 40 per cent. 
5. Temperate and hot... 40 16 J 2 within hot zone 173 = 69 per cent. 
GL TSUGE Orally 44. <2s prance soo! 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 
