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Show 1 9 0 3 . ] TRANSPOSITION of m am m a l ia n testes. 3 2 9 is well known, they are " huge, heavy, clumsy creatures, with bent legs so short that the belly seems almost to drag 011 the ground." The Subungulata comprise the Hyracoidea and the Proboseidea. The ancestry of the members of both these suborders is as yet undecided, their status, decidedly low in the scale, being obscure. The Hyracoidea are animals of about the size of a rabbit or somewhat larger, and " resemble small marmots." They possess a " short, fat body" with " weak and short feet." " In most species there is a complete adaptation to a life among the rocks," by possession of curious clinging habits resembling those of the Geckos. They are " agile in their sports, but rather lazy where food is abundant." Owen states that " the testes are abdominal, below or beyond the kidneys." The low status of the Proboseidea is shown by several anatomical traits, such e. g. as the possession of two venae cavae and the structure of the limbs. These animals have been well described as " peaceable colossi." Their gait is " pretty slow, though the Colossus can run very fast when once in full career, but this pace never lasts very lung and is always maintained in a straight line." Owing to their huge size Elephants never gallop. The most active members are the " rejected males"-such extra activity thus being neutral so far as the inheritance of any tendency to testis descent is concerned. Elephants are vegetable feeders and are " gregarious, generally inoffensive and even timid, fond of shade and solitude and the neighbourhood of water." The testes are permanently abdominal -a fact explicable by habits, though phylogeny alone can afford a complete solution. Here, as possibly also in the case of the Nasicornia, it may be pointed out that the huge size of these animals itself implies inactive ancestors, for, according to one of the conditions of growth enumerated by Spencer, great activity is antagonistic to increase by bulk, and the occurrence of the latter negatives the past existence of the former. The order Carnivora is subdivided into the Fissipedia and the Pinnipedia. The members of the former group are all exceedingly active animals of large size, and, together with the Ungulata, include the swiftest of terrestrial animals. Their testes, needless to say, reside in a well-defined scrotum. The Pinnipedia afford an interesting illustration of the secondary operation of natural selection. In the Otariidae the " hind feet are turned forwards under the body, and aid in supporting and moving the trunk as in ordinary mammals............They spend more time on shore, and range inland to a greater distance than the true seals." In the Otariidae the testes are " suspended in a distinct external scrotum" \ On the other hand, in the Phocidae, " the hind limbs are directed so far backwards that they continue the horizontal direction of the vertebral column........... They move on land only with difficulty by fixing themselves with their flippers in front and pulling up their hinder parts, then drawing their bodies up into a curve and 1 0\^en states that the scrotum is not distinct. |