PHYSIOLOGICAL ANIMAL GEOGRAPHY 605 
3 Formations of savannas and grasslands. 
a Warm savanna and steppe formations (fig. 19, 3a). 
Environment: Dry season in spring; scant rainfall; grassland with scat- 
tered thorny trees, occasionally thickets, and dense forests along pee 
streams. 
Distribution: The great plains of Africa (Roosevelt, 09-10), and South 
America. 
b Cool savanna formations (fig. 19, 3b). 
Environment: Similar to the warm in aspect, but more often with trees 
in groves. 
Distribution: A narrow belt nearly surrounding the Great Plains, Uru- 
guay, Australia, and eastern Siberia (Brehm, ’96). 
e Cool steppe formations (fig. 19, 3c). 
Environment: Cool, dry, winters cold, grassland with trees only along 
the principal streams. 
Distribution: The great plains of North America (Craig, ’08; Seton, ’09), 
south central Asia (Brehm, ’96), De La Plata southward to Patagonia 
(Hudson, ’92). 
4 Formations of forests with broad, thick leaves (fig. 19, 4). 
Environment: Subtropical conditions with winter rain and hot, dry 
summers. 
Distribution: California, the Mediterranean region, Chile (near Val- 
paraiso, Darwin ’45), South Africa, southwest Australia. 
5 Formations of deserts and scrub areas (semi-desert). 
Environment: Various types of arid condition with thorny vegetation. 
a Scrub or semi-desert formations (fig. 19, 5a). 
Distribution: Mexico, Texas and Central America (Belt, ’88; Bailey, 
05), eastern Brazil, southern South America, arid Australia (in part), 
northeastern Africa (Plowden, ’68), India, and China. 
b Desert formations. 
Distribution: Southwestern North America (Merriam, 90), South America, 
Sahara and Arabia (Brehm, ’96), central Australia and south Africa. 
6 Tundra formations. 
a Arctic tundra formations. 
Environment: Cold, treeless, with short cold summers. 
Distribution: Circumpolar (fig. 19). 
b Alpine tundra formations. 
Environment: Similar to a. 
Distribution: Mountains above the tree line. 
7 Formations of fresh water. 
a Still water formations (lakes, ponds and sluggish streams). 
b Turbulent water formations (swift streams and eroding lake shores). 
8 Formations of the sea and its shores (amphibious formations, principally 
breeding on shore, feeding in sea). 
a Ice-bound shore formations (Arctic) (Brehm, ’96; Shackleton, ’10). 
b Tropical and temperate shore formations. 
ec Oceanic Islands formations (the island fauna, representing the migra- 
tion of land animals by sea) (Wallace, ’92). 
JOURNAL OF MORPHOLOGY, VOL. 22, No. 3 
