656 GIIORDATA. 



added two extinct groups, iSiuirurre and Odontornithes, which had 

 teeth. 



■45. The Mammalia have a double occipital condyle, hairy skin, 

 and milk glands in the female for the nourishment of the young. 



46. Other characters are the homoiothermous condition, the 

 complete separation of the heart, the modification of parts of the 

 visceral arches into the ear bones, high development of the denti- 

 tion (formation of roots, usually heterodont and diphyodont). 



47. The mammals are divided into Monotremata, Marsupialia, 

 and Plaeeutalia. 



48. The Monotremata are egg-laying mammals with persistent 

 cloaca; they have a distinct coracoid and an episternum. 



40. The Marsupialia are viviparous, but the young, on account 

 of imperfect uoiTrishment (usually no placenta), are born early and 

 usually carried in a marsupiuin (marsupial bones). 



50. In the skeleton the inflected angle of the lower jaw is char- 

 acteristic. The urogenital apparatus is separated from the anus 

 by the perineum ; uterus and vagina are double. 



51. The Placentulia produce well-developed young which are 

 nourished in the uterus by a placenta; they have no niarsupium 

 nor marsupial bones. The vagina is single (Monodelphia), the 

 uterus simple or paired. 



53. The clawed Edentata and the Cetacea and Sirenia, which 

 have flippers, have a degenerate dentition (teeth monophyodont or 

 lacking). 



53. The hoofed unguhites (Perissodactyla and Artiodactyla), 

 the Proboscidia, and the small clawed Eodentia are joreeminently 

 herbivorous. 



54. The Chiroptera, which have a flying membrane (p)atagiuni), 

 are partly herbivorous, partly insectivorous. 



55. The small Insectivora (with small canines and no carnas- 

 sial) and the Carnivora (with strong canine and carnassial molar) 

 are carnivorous. The Carnivora arc subdivided into the terrestrial 

 Fissipedia and the aquatic Pinnipedia. 



56. The Prosimia3 and Primates have a niore or less indifferent 

 dentition. They have largely or entirely replaced claws by nails, 

 and are largely provided with grasping hands and feet. The 

 Prosimia' are lower, the Primates more highly organized. 



57. The Primates are subdivided, according to the position of 

 the nostrils, the development of the tail, as well as the character of 

 the dentition and the foot, into the PlatjTrhinae, or monkeys of the 

 New World, the Ciata,rrhina>, or apes of the Old World, and the 

 Anthropina.', or man. 



