TRIASSIC PERIOD. 423 



include species that have the tails only half-vertebrated, or not at 

 all so. And thus it is that the progress of the Ages, as first observed 

 by Agassiz, is marked in the tails of the Fishes. 



that chew the cud, which are all two-toed, as the Cow, Sheep, 

 Antelope, Anoplotherium, Camel. (2) The Omnivores, as the Hog. 

 (2.) Perissodactyls, or odd-toed. Dorso-lumbar vertebrae more 

 than nineteen. Horns, when any, never in pairs. Include (1) the 

 Sulidungulates (solid-hoofed), or one-toed, as the Horse, Ass, 

 Anchitherium, Hipparion [Macrauchenia?]. (2) Midtungulates, 

 having three or five toes, as the Tapir (hind feet three-toed, 

 front four-toed), Rhinoceros (three-toed), Palseotherium (three- 

 toed), Lophiodon, etc. (3) Proboscidia, as the Elephant, Mas- 

 todon, having five toes, and. a proboscis, with tusks from one or 

 both jaws. 



4. Mutilates. — The limbs short and paddle-like, for swimming. (1) 

 Cetaceans, as the Whales. (2) Sirenia, as the Lamantin or Manatus, 

 and the Dugong or Halicore. 



III. MlCROSTHENES. 



1. Chiropters, or Bats (analogues of the Quadrumana). — Having wing- 



like expansions of the fore limbs. Manimae pectoral. Hibernate. 

 Subdivisions — (1) Insectivores, or Insect-eaters, and (2) Frugivores, 

 or Fruit-eaters. 



2. Insectivores (Insect-eaters, analogues of the Carnivores). — The 



molar teeth studded with conical points and associated with inci- 

 sors and canines. Legs short. Slow in movement, as the Mole, 

 Shrew, Hedgehog. 



3. Rodents, or Gnawers (Fruit and Root eaters, analogues of the Her- 



bivores). — Molars with flat, grinding summits; two long incurved 

 incisors in each jaw, separated by a wide space from the molars: 

 as the Mouse, Squirrel, Beaver, Porcupine, Capybara. Many hiber- 

 nate. 



4. Brutes, or Edentates (analogues of the Mutilates). — The incisors and 



canines, with a rare exception, wanting, and some species wholly with- 

 out teeth. The sacrum made of two united vertebrae, as in Reptiles. 

 Twenty-three ribs, — an unusual number, also a Reptilian feature. 

 The teeth without enamel, and none ever replaced by a new set. Legs 

 with claws, but motions all slow. Include — 



(1.) The Dasypus or Armadillo group, covered with scales or a 

 carapax, — e.g., Armadillo or Dasypus, Chlamydophorus, Glyp- 

 todon, Chlamydotherium, Pachytherium. 



(2.) The Bradipus or Sloth tribe, without a carapax or coat of 

 mail, and mostly covered with hair; furnished with molars, as 

 the Sloth, Megatherium, Megalonyx, Mylodon, Scelidotherium. 



(3.) The Myrmecophagus or Ant-eater tribe, as the Myrmecopha- 

 gus (Ant-eater), Orycteropus. 



IV. Semi-oviparans, or Ooticoids. 



1. Marsupials (from marsupium, a, pouch). — Young prematurely born, and 

 carried while still in the embryonic state in a pouch over the belly,. 



