IV. VERTEBRATA: MAMMALIA, PRIMATES 



573 



alone clawed. Lemur; Stenops, loris. The tertiary P.'vchylemurid^ and An- 

 APTOMORPHiD^ are close to the most primitive mammals, creodonts, and 

 insectivores. The Galeopithecid^ (p. 564) are often placed here. 



Order XII. Primates. 



The most highly organized mammals, the monkeys, apes, and man, are 

 united in a single order because of their great agreement in features of clas- 

 sificatory value. If we here, as elsewhere, ignore grades of intelligence and 

 regard alone greater or lesser anatomical resemblances, we are forced to the 

 conclusion that the anthropoid apes are much closer to man than to the lower 

 monkeys. The primates have, in common, nails on all the fingers and toes 

 (e.xcept Hapalidae), orbits separated from the temporal fossae by a bony wall, 

 and a cerebrum which covers the other parts of the brain (fig. 600, c). They 



Fig. 621. — Hand and foot of gorilla, c, capitatum; ca, calcaneus; cii, cuboid; 

 h, hamatum; I, lunatum; mc, metacarpals; ml, metatarsals; n, naviculare; p, pisiforme; 

 ph, phalanges; s, scaphoid; t, triquetrum; ta, talus; td, trapezoid; /r, trapezium; I-V, 

 digits; 1-3, cuneiformia. 



have a single pair of pectoral mammae, uterus simplex, and discoidal placenta. 

 The dentition is essentially the same throughout; in the Platyrrhinas i\M, in the 

 Hapalidae |ill, in the Catarrhinae and in man liif. Yet there is a tendency to 

 variation, since in the chimpanzee and in man the third molar (wisdom tooth) 

 is in process of degeneration, while in the orang a fourth molar often occurs. 

 The molars are bunodont. 



As in the lemurs and opossums, the thumb and great toe can be opposed to 

 the other digits, so that an ape can grasp objects with either hand or foot. In 

 man this opposability of the thumb is increased, but that of the great toe, in 

 consequence of the upright position, is only retained to a slight degree by chil- 

 dren and primitive people. On this peculiarity rest the names Bimana, for 

 man, and Quadrumana, for the apes and monkeys. But it must be emphasized 

 that the apes do not have a hand, but rather a grasping foot, on the hinder 



