DISTRIBUTION OF ORGANISMS. 215 



JBovidce (aurochs, bison, buffalo, ox), leading on by such inter- 

 mediate forms as the ovibos or musk-ox to the sheep ; and the 

 Cervidce (elk, deer), leading on to the goat ; the animals of low 

 and alluvial grounds thus, as usual, passing into smaller species 

 adapted to more inland and elevated situations. 



The last mammalian order is that which Linnaeus called 

 Primates, comprehending, however, not only the monkeys and 

 lemurs, and the Cheiroptera or bats, but the Sloths (Brady- 

 podidce) ; which Cuvier, merely from their want of certain 

 teeth, placed elsewhere. 1 For this order there remains (with 

 a long interval) a basis in the Delphinidce, the last and smallest 

 of the cetacean tribes. This affiliation has a special support 

 in the brain of the Dolphin family, which is distinctly allowed 

 to be, in proportion to general bulk, the greatest amongst 

 mammalia, next to the oran-outang and man. We learn from 

 Tiedeman, that " each of the cerebral hemispheres is composed, 

 as in man and the monkey tribe, of three lobes an anterior, a 

 middle, and a posterior ;" and these hemispheres " present much 

 more numerous circumvolutions and grooves than those of any 

 other animal." Here it might be rash to found anything upon 

 the ancient accounts of the dolphin its familiarity with man, 

 and its helping him in shipwreck and various marine disasters, 

 although it is difficult to believe these stories to be altogether 

 without some basis in fact. There is no doubt, however, that 



1 The sloths have been raised from association with the ant-eaters and 

 armadillos to the Primates, by a French naturalist, in consideration of 

 the complete nature of the fore-arm, the head of the radius being round 

 and apt for rotation ; also, from the thorax being rather wide than deep, 

 and from the form of the trunk in its lower part. Mr. Owen is opposed 

 to the translation ; but it is supported by Mr. Edward Newman, a living 

 zoologist of the first character. The following are Mr. Newman's rea- 



O *~ ' 



sons : 



"The face of the sloth is round, short, and remarkable for its almost 

 human expression, a character even more observable in this animal than 

 in the majority of monkeys. The structure of the skull and teeth also 

 exhibit some approaches to the monkeys, but none to the ant-eaters. 

 The size, figure, and general external appearance is that of a monkey. 

 The mammae are two only, and these are pectoral. The feet are always 

 used as hands for grasping and climbing, and never as feet for walking 

 or running on the ground. The sloth spends his time entirely in trees, 

 among the branches of which he travels with wonderful rapidity." 

 System of Nature, 1843. 



The Physiologist who has supplied some MS. notes on these pages here 

 remarks : "The characters enumerated above are rather adaptive than 

 essential. In the most essential characters, those of the nervous and 

 generative systems, the sloths are very low. Moreover, they are inti- 

 mately connected with the Mylodon, Megatherium, etc., which have 

 many reptilian affinities." 



