1 88 ANIMAL LIFE PAST AND PRESENT. 



although the ardent palaeontologist cannot but help 

 wishing that he had the power of casting a glance on 

 those long-past periods when our earth was compara- 

 tively young and inhabited by the marvellous host of 

 extinct animals whose modern descendants have so 

 woefully diminished both in size and numbers. 



Making, however, the best of our opportunities, and 

 not wasting time in futile regrets at being unable to 

 recall that which has passed away for ever, we may, 

 before proceeding to the consideration of the fossil 

 forms, briefly contrast a few of the more striking 

 features in the organisation of a dog (under which 

 term it will be convenient to include wolves, jackals, 

 foxes, et hoc genus omne) with those of a bear, as in all 

 such investigations it is advisable to make ourselves 

 thoroughly acquainted with the well-known before we 

 attempt the consideration of the comparatively un- 

 known. 



A dog, in this general sense, is characterised exter- 

 nally by his comparatively slight and slender build, 

 long limbs, well-developed tail, and above all by the 

 circumstance that he walks only on his toes or, as 

 naturalists say, is digitigrade his wrist and heel being 

 carried far above the ground. The figure of the jackal 

 (Fig. 56) gives a good idea of the external form of the 

 dogs. A bear, on the contrary, is of an exceedingly 

 bulky and clumsy build, has short and thick limbs, a 

 mere apology for a tail, and in walking applies the 

 whole length of his foot to the ground, or, in other 

 words, is plantigrade. It will be unnecessary to enter 



