No. 425.] LAW OF ADAPTIVE RADIATION. 359 
remains are often found together. Yet if we examine anal- 
ogous types living to-day, we see that they do not frequent 
exactly the same feeding ranges nor do they subsist upon 
exactly the same food; they thus do not compete. Good illus- 
trations of this local adaptive radiation are seen in the distribu- 
tion in Africa of the closely allied square-lipped Rhinoceros 
simus with hypsodont. teeth, which lives upon grasses, and the 
more pointed-lipped R. bicornis with brachyodont teeth, which 
lives mainly upon shrubs. Both species belong to the same 
phylum of rhinoceroses. Among fossil types closely related 
to the above we.observe similar cases, such as the coexistence 
in the lower Pleistocene of the hypsodont R. antiquitatis 
(woolly rhinoceros) and the brachyodont A. hemitechus. 
If carried farther than in the above instances, we may be 
justified in placing these local adaptive radiations in separate 
subfamilies, because in many cases they give rise to distinct 
and long-persistent collateral phyla. 
Examples of this kind are numerous among the ancient 
Perissodactyla or ungulates related to the horses, tapirs, and 
rhinoceroses, as seen below. 
I. Stout-Foorep, HEAVY- IIl. SLENDER-FOOTED, 
LIMBED PHYLUM LQieHT-LIMBE D, 
CURSORIAL PHYLUM. 
Families. Subfamilies. Subfamilies. 
1. Palæotheriidæ Palzotheriine £8.) (Mid- Palaplotheriine (Middle 
dle Eocene to Lower Eocene to Lower Oli- 
Oligocene) gocene) 
2. Titanotheriidze (Mid- Telmatototheriinz 77! 
3. Hyracodontide 
Paleosyopine Ø. 
le Eocene to Upper 
Eocene 
Hyrachyine B. (Middle 
(Middle Eocene to Up- 
per Eocene) 

Vin meu B. mmc 
to Upper Eocene) Eoce 
Lophiodontinz 7. (Mid- 
dle to Upper Eocene) Colo 
cene) 
pper 
4- Lophiodontidz Helaletine B. feud 
don 
tine ZB. crai 
It will be observed at once that there is no inherent corre- 
lation between brachyodontism and brachypody, or hypsodontism 
and dolichopody, or elongation of the feet, as we might have 
anticipated, although hypsodontism is gradually developed in 
1 B. = brachyodont; H. = hypsodont. 
