702 Hans GADow, 
Although this mode of caleulation gives a surprisingly regular, 
steady result, it has one weakness. With each new level some species 
are dropping out whilst others are added, for instance at the 
7000' level Bufo punctatus and Ayla copei have dropped out from 
the list of changed species, whilst Ahadinea laureata enters as new. 
Thus it comes to pass that the 6000, 7000 and 8000 ft. levels each 
possess 4 completely changed species although these are not the 
same in every case. This unavoidable play of facts may vitiate 
the statistical result. 
Let us therefore make another calculation, taking census for 
every level of those species only which do not ascend beyond such 
level, regardless of the fact whether this is their actual upper limit 
or whether they have already dropped out lower down. 
| Thus up to 5000‘ we have to consider 28 species; of these 
perhaps only Streptophorus does not quite reach sealevel. 
Up to 6000‘ we have to consider 31 species. Again nothing 
has happened, excepting that Dufo punctatus is introduced as the 
only entirely temperate species, whilst all the others still proclaim 
themselves as hot country species, none of them having left the 
Lowlands. 
Up to 7000‘ we have to deal with 37 species. A great change 
is manifest: Bufo punctaius as an entirely temperate species; Ayla 
copei almost entirely temperate, nearly leaving the Hotlands. Alylodes 
punctatus in much the same condition; Dufo intermedius and Trimor- 
phodon ypsilon finding their toplevel at 7000’ and entering the list of 
those which begin to leave or give up the Hotlands. 
This seems indeed instructive. Of the 7 species (if we include 
H. copei) which here at 7000'° have reached their toplevel, only 
2 still retain theis footing at sealevel (Elaps and Frhadinea), all the 
others having left it. Or to put it more forcibly: being in the act 
of giving up the Hotlands they thereby are converting themselves 
into “temperate” species, such as H. copei has become almost, 
B. punctatus completely. 
Up to 8000‘ 43 species have to be considered, nearly the whole 
total: the Southerners are practically exhausted. Thus far they 
have been able to ascend at all, besides the hardy, indifferent 
long-ranged Hylodes rhodopis, so that of the 5 species to which 
8000‘ means actual toplimit, 4 have given up the Hotlands and the 
fifth, H. eximia has given up at least the Atlantic, i. e. the moist, 
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half of the Tierra caliente. Moreover out of these 4 or 5 changed 
