368 THE ANIMAL KINGDOM. 



Africa, Ceylon, Bay of Bengal, Indo-Malayan Archipelago, North coast of 

 Australia ; (3) the Cetacea, including toothed and whale-bone Whales ; (4) the 

 Insectivora, a group of small inconspicuous Mammals with a wide distribution ; 

 (5) the Chiroptera or Bats; (6) the Rodentia, an order widely and evenly distributed 

 with a large number of families ; (7) the Ungulata, an order comprising a large 

 number of dissimilar groups, including the Hyracoidea, Probosddea (Elephants), the 

 Perissodactyla (Horse, Rhinoceros, Tapir), the Artiodactyla, subdivisible into the 

 Ruminantia (Cows, Sheep, Goats, Antelopes, Deer, Camels, Giraffe), and the non- 

 Ruminantia, i. e. the Hippopotamus and Suidae ; (8) the Carnivora, including a 

 sub-order Fissipedia with the groups Aeluroidea (Cat-group), Cynoidea (Dogs), and 

 Arctoidea (Bears, Weasels, &c,), as well as a sub-order Pinnipedia, or the Seals ; (9) 

 the Primates, which includes the Lemuridae^ Simiidae (Monkeys and Apes), and 

 the Hominidae (Anthropidae] or Man. 



There are many extinct groups, especially groups allied to Ungulata. For 

 these, see Marsh's papers in the American Journal of Science; his Deinocerata 

 in the United States Geological Survey, x. 1884; Cope, ' Vertebrata of Tertiary 

 formations of the West,' Report of U. S. Geological Survey of Territories, iii. 1885 ; 

 his papers in the American Naturalist for the last few years ; Flower, ' Mammalia ' 

 (supra) ; Wallace, ' Distribution of Animals,' 1876, caps. vi. vii. viii; Schlosser, 

 1 Stammesgeschichte der Huftthiere,' &c. M.J. xii. (i), 1886. Tritylodon longaevus, 

 a Triassic South African Mammal of doubtful affinities, Owen, Journal Geol. Soc. 

 40, 1884. 



SUB-CLASS METATHERIA. 



THIS sub-class contains the single order Marsupialia with a large num- 

 ber of families, one the Didelphidae, confined to America, the remainder 

 to the Australian and Austro-Malayan sub-regions. The auditory bulla is 

 formed by a process of the alisphenoid and the tympanic is a loose semi- 

 ring. The carotid canals pierce the basi-sphenoid as in Cetacea, among 

 Eutheria, and as in Sauropsida. The palate often has unossified vacuities 

 and the angle of the lower jaw is inflected except in Tarsipes. The median 

 inferior piece of the atlas vertebra may remain unanchylosed (Thylacinus), 

 or be absent altogether (Phascolomys, Macropus, &c.). There are as a rule 

 two epipubic or ' marsupial } bones. In the brain the corpus callosum is 

 small and the anterior commissure large. The retinal cones contain 

 coloured oil globules. The crowns of the teeth conform to very different 

 patterns according to the habit of life, i.e. carnivorous, insectivorous, 

 rodent, &c. There may be more than three incisors on each side in the 

 upper, rarely in the lower, jaw, and the number in the upper and lower is 

 equal only in Phascolomys, which has two above and below. There are 

 three praemolars and four molars above and below on each side, reversing 

 the numbers usual in Eutheria. The last praemolar alone has a milk pre- 

 decessor, and it is not certain that this is the case in all forms. The dentinal 

 tubes are frequently continued on into the enamel. The character of the 

 stomach varies much with the food. The anus opens in the female, except 



