95 
GRADATION AMONG ANIMALS. 
-SECONDARY. TERTIARY. 
PRIMARY. 
RADIATES. 
MOLLUSKS. ARTICULATE! 
Ss. VERTEBRATES. 
r 
Present, +.. +++ 
Pliocene, --+-- 
Polyps. Acal shi echine Acephal on a Senha Worms: Crust . Insects. Fishes. Reptiles. Birds. Mamnialia. 
f ele wwe ew welewe nes el meme eenl er eaeeeslereseriasaseelianene weeeleeereene 
Eocene,-+++++ 
Cretaceous, «++ 
Azoic. 
Miocene, ---+-|- 
Turassic,ss+. ++] -eee . 
‘Triassic,.---++ ele tend seve! 
Permian, .+++«|.s0e00- 
? Carboniferous, |,...... 
Devonian,-«++|-.-++ 
co enwceleceesenene 
Silurian, ...Polyps. Avnleplis. Echino- acoph 
seeeee} True Mammalia. 
radeak perenaunlersert ss) smemeie eweues seceleceeee|++eMarsupials...++ 
pce eae | aynesenls cerns selsanane «| araiasaters lly wins statis ie siniets |areie a BIOS: sie inse ae dining 
viaieipie of cia sts sleet Eaie sie’be apenas ssoeeInsects.e++|.+-Reptiles..++ +++ eereererr rs 
Jp, Gastero- Cephalo- 
derms. 
poda. 
poda. ‘Worms. Crustacen.. + 
