742 ANATOMY OF VERTEBRATES. 



smooth and polished, not villous like the cotyledons of the Rumi- 

 nantia ; from which they likewise differ in projecting inward 

 toward the cavity of the allantois, like the so-called cotyledons 

 of the sloth : they are not mere precipitates of inspissated matters 

 of the allantoic fluid, like the 'hippomanes' of the Mare. 



A male and female Indian Elephant paired December 18, 1863, 

 and at other times up to January 8, 1864, when they were kept 

 apart. For twelve months there was no conspicuous increase of 

 the abdomen : after that period it was obvious to close inspection, 

 on the left side : then the mammary glands enlarged, with slight 

 occasional oozing of milk ; and on August 3, 1865, the young 

 was born ; it stood 2 feet 10 inches high, and weighed 175 lbs. 

 Thus the period of gestation, reckoned from the date of first 

 coitus, is 593 days. 



The Hyrax has an annular placenta more subdivided than in 

 the Elephant. The venous blood returns from it at three places, 

 the centres of as many divisions of the belt, which, however, are 

 continuous by thinner portions of placental substance. The villi 

 are imbedded in decidual substance, and the surface of its attach- 

 ment to that remaining on the uterus is less limited than in the 

 Elephant. The placental zone seems relatively tighter, the ends 

 of the chorion swelling out more, than in Carnivora. The perisso- 

 dactyle number of ribs — twenty-two pairs, the simple stomach 

 and complex crecal structures, the hoofs of the unsymmetrically 

 tetradactyle fore-foot and tridactyle hind-foot, as in a larger 

 extinct hornless rhinoceros, the close repetition of dental cha- 

 racters in the diminutive existing species, not merely as to pattern 

 of grinding surface of molars, but of kinds and manner of growth 

 of all the teeth, the incisors being developed as in Rhinoceros in- 

 cisivus, 1 demonstrate the low taxonomic value of the placental 

 character, according to which the Hyrax, as well as the Elephant, 

 would be classed with the Carnivora. 



§ 404. Development of Carnivora. — In the fcetal Cat, about 

 the middle of the period of gestation, the chorion, fig. 578, a, a, 

 is a curved arc 6 inches in long diam., by 2 inches in short 

 diam., with obtuse ends; it is girt in the middle by an an- 

 nular placenta, b, li inch broad : the zone is concave transversely 

 within, of a mingled grey and red colour when uninjected : the 

 chorion on each side of the placenta is slightly folded, and of a 

 reddish colour. The foetal surface of the placenta is lobulated : 



1 He must have counted much upon the ignorance of his auditors or readers who 

 could affirm that the ' Hyrax hangs by Rhinoceros mainly by the pattern of its molar 

 teeth.' cclxx". p. 111. 



