MAMMALIAN SEXUAL CHARACTERS 151 



ancestors which had a scrotum : in either case the 

 position of the testes corresponds to the absence of 

 what Dr. Woodland calls impulsiveness in progres- 

 sion. The Fissipedia offer an instructive example, 

 for while the Otariidae have the hind feet turned 

 forward and can move on land somewhat like 

 ordinary Mammals, the Phocidae cannot move their 

 hind legs independently or turn them forward, and 

 can only drag themselves about on land for short 

 distances. In the former the testes are situated in a 

 well-defined scrotum, in the latter these organs are 

 abdominal. The Phocidae are probably descended 

 from Mammals of the terrestrial type with a scrotum, 

 which has disappeared in the course of evolution. 

 Perhaps the most curious exception is that of the 

 elephants, in which the testes are abdominal. Here, 

 in consequence of their structure and massive shape, 

 locomotion is usually a walk, and though they 

 run occasionally the gait is a trot, not a sustained 

 gallop, and leaping is out of the question. Sloths 

 which hang from branches upside down have ab- 

 dominal testes, but even here they are in a posterior 

 position, between the rectum and the bladder, so 

 there has apparently been a degree of dislocation, 

 probably inherited from ancestors with more ter- 

 restrial habits. 



The fact that the ovaries do not occupy normally 

 a position similar to that of the testes is in accordance 

 with the theory, for they are very much smaller than 

 the testes; and yet they have undergone some 

 change of position, for they are posterior to the 

 kidneys. 



The facts agree also with the hormone theory, for 

 it is to be noted that although the development of 



