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Show 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 lowlands, 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. Everything 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 ce 1. Cold or cool only 22 17 2. Cold and temperate. 6 5 3. Cold to hot ............ 13 10 4. Temperate only 12 9 5. Temperate and h o t ... 11 9 6. Hot only ................ 67 51 131 101 1 > within cool zone 38 sp.= 30 per cent. J]y within i temperate zone 42 = 32 per cent J } within hot zone 91 = 70 per cent. ) (groups 6 + 5+ 3 ). 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 32.. CCoolldd aton dh otet m.p..e..r.a..t..e... 2204 89 -6 j ( 4. Temperate only 15 6 5. Temperate and hot. .. 40 16 6. Hot only ............ 109 43-6 250 100-2 within temperate zone 99 = 40 per cent. ithin hot zone 173 ■ (groups 6 + 5 + 3). J 7 within = 69 per cent. 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 |