HIPPOPOTAMUS. 



753 



The great fossil hippopotamus has been found in the 

 clay deposits of many countries, as, for instance, in 

 the valley of the Arrio in Italy, in the south of France, 

 near Paris, at Kirkdale in Yorkshire, and at Brent- 

 ford, in the valley of the Thames, so that it must 

 have been a very general inhabitant of Europe ; and 

 Europe must then, in the characters of its waters, 

 have resembled what Africa is now, in those places 

 where the hippopotamus is found in the living state. 



Climate, at least so far as depends upon tempera- 

 ture, does not form any necessary or important part 

 of this great question ; for as we have the actual fact 

 of an elephant having existed in the extreme north, 

 with a covering better tilted for protecting it from 

 snow and cold than that of any animal now living, 

 while in its anatomy, and therefore by inference in its 

 mode of life, it did not differ much from the elephant, 

 as now found in Asia and Africa, we have no reason 

 to doubt that the other large pachydermata of the 

 north, which are also extinct, were equally adapted to 

 a climate even more rigorous than that of the places 

 where their bones are found at the present day. 

 There are some indications in the form of the fossil 

 skeletons, especially in the parts fitted for motion, 

 which would lead us to suppose that those hippopo- 

 tami of ancient days were more active than their con- 

 geners of the present time. There is more strength 

 in the heads of the bones, as well as more length ; 

 and both of these indicate that the muscles were more 

 powerful ; the teeth are also stronger, and there are 

 some differences in the cranial bone, which perhaps 

 warrant us in concluding that the animals had more 

 resources. 



What the state of the earth was when the hippopota- 

 mus was common in Europe, we cannot tell, and shall 

 never, in all probability, arrive at in a satisfactory man- 

 ner. But we hare no reason to believe that the axis of 

 the earth's rotation had a different position from what it 

 has at present ; and though the obliquity of its orbit 

 varies, the variation is slow, and is understood to act 

 on their limits, or to involve in itself the means of a 

 return to the same angle after a very long period ol 

 years. Hence we cannot suppose that the seasonal 

 action of the sun was very different then from what it 

 is now ; for the notion, which has been at different 

 times altered of the strake of a comet, or some such 

 imaginary cause, tilting the axis of the earth from the 

 perpendicular, is not only gratuitous, but absurd. 

 We have no reason to believe that the earth would 

 be very much affected by a comet, even though it 

 were to pass through one, as the satellites of Jupiter 

 were not in the least disturbed by a comet which gol 

 within their sphere of action. Besides, the motion ol 

 the earth on its axis is not in any way affected by any 

 body in the heavens, or by any known quality or cir- 

 cumstance of the earth itself. We can see no reason 

 why it should be different now from what it was al 

 the moment of the earth's creation, or why it should 

 become different at any future time of the earth's 

 duration, oven if all the rest of the solar system were 

 destroyed, and the earth stood still in its orbit. 



In contemplating our own country and latitude as 

 being inhabited by these great pachydermata, whicl 

 are now found only in the southern parts of the ok 

 continent, we must therefore assume, that the annua 

 action of the sun upon the earth must have been 

 nearly the same as it is now. That the earth ii 

 our latitudes must have been more humid, am 

 covered with a ranker and ruder vegetation in the 

 NAT. HIST. VOL. II. 



lays of those pachydermata than it is now is 

 jerfectly obvious ; inasmuch as such animals are 

 ound only in places where there is a rank vegeta- 

 ion. Water and vegetables are much less affected 

 >y changes of temperature than the solid and inor- 

 ganic parts of the earth, and therefore we may pre- 

 .ume that, in these former times, there was much 

 greater uniformity of the seasons a different vegeta- 

 ion certainly, but one which underwent less marked 

 seasonal changes. The true ferns, and other plants 

 analogous in many of their characters to those that 

 are now met with only in the warm latitudes, prove 

 .his. But the very same circumstances must have 

 ;ended to prevent that drain of heat from the polar 

 atitudes to the equatorial ones which certainly now 

 takes place ; for much of the action of the sun goes 

 off to the atmosphere by radiation, and as the air on 

 the surface upon which this radiation of heat chiefly 

 tells, is always creeping toward the equator, it must 

 follow that the cold latitudes are cooled by this 

 means, and that they are more cooled in proportion 

 as the equatorial parts are more converted into desert. 

 This inquiry is a most tempting one, and if we pay 

 even the very slightest attention to these remains of 

 the old world which we meet with at every step, we can 

 hardly avoid entering upon it ; but the links in the 

 chain of evidence are so broken that, in the meantime, 

 it is little else than a pleasing dream. The labour of 

 many hands, and the wisdom of many heads, will still 

 be required before the subject is so well explained as 

 to bring it within the limits of popular science. 



The middle-sized hippopotamus is the next of the 

 fossil species in point of size, and it, as well as the 

 smaller ones, seems to be wholly extinct, nor have 

 any vestiges of it been found in those parts of the 

 world which the living hippopotamus inhabits. This 

 species, of which the remains have, we believe, been 

 hitherto found in France only, seems to have been 

 about the size of the common hog, and as this is found 

 in the calcareous tufa, which, though a fresh water 

 formation, is in all probability older than the debris in 

 which the remains of the larger one are found, we 

 may perhaps conclude that it became extinct at an 

 earlier period of the earth's history. Only mutilated 

 fragments of the skeleton of this" animal have been 

 found ; but still there are enough to show that it was 

 a hippopotamus, though different in some respects 

 both from the larger fossil one, and from that which 

 still exists in the living state. 



The small fossil hippopotamus has been found in 

 greater abundance than the last species. It has been 

 found in the lower valley of the Garonne, and the 

 flats between the estuary of that river and the Pyre- 

 nees, in accumulations of bones at Gibraltar (the 

 whole rock there is, in fact, curious in this respect), 

 in Dalmatia, and in some other places. It is less 

 than the common hog ; and the worn state of the 

 teeth shows that it is not the young of any animal. 

 The tusks are crooked, rather more so perhaps than 

 in the living rhinoceros ; but still their shape and 

 curvature are quite different from those of any species 

 of hog ; the jaws are rather larger, and the muzzle not 

 so broad as in the living species. What effect 

 these differences may have had in modifying the 

 habits of the animal, we are unable to tell ; but the 

 general structure clearly shows that it belongs to the 

 hippopotami genus. 



The least fossil hippopotamus is less than either o 

 the former. The remains indicate an animal about the 

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