FOSSIL LEMURS 237 



writer, who makes this comparison, that in both cases the structure is one specially 

 adapted for long-continued grasping without change of position. 



FOSSIL LEMURS 



We have already incidentally referred to the occurrence of several fossil lemurs 

 in the lower Tertiary strata of Europe ; but it remains to be mentioned that other 

 species have been found in the corresponding rocks of North America. This is a 

 very curious and highly important circumstance, since it suggests that while the New 

 World monkeys and marmosets, which have very lemur-like molar teeth, may have 

 taken their origin directly from the extinct lemurs of that hemisphere, the Old World 

 monkeys may have had an independent origin from the ancient lemurs of Europe. 



Curiously enough, although the remains of lemurs have been known for very 

 many years from the lower Tertiary rocks, both of Hampshire and France, it is only 

 quite recently that they have been recognized as such, having been long regarded as 

 belonging to small hoofed Mammals. One of these groups of lemurs, represented by 

 several species of different, though relatively small, dimensions, occurring both in 

 England and France, has been described under the name of Microchoerus ; the term 

 meaning "small pig," and having been applied from the supposed affinity of the 

 creature to the hoofed Mammals. These animals were undoubtedly lemurs nearly 

 allied to living forms, their skulls being very like those of the galagos, although 

 their upper premolar teeth more nearly resembled those of the mouse-lemur.s. Like 

 all other fossil lemurs, they are, however, distinguished from living forms by the 

 circumstance that the place and form of the lower tusk is not taken by the first of 

 the lower premolor teeth (see p. 203). This is a very important circumstance, since 

 it shows that these ancient lemurs were what zoologists call less specialized than 

 their living relations, and also removes any difficulty as to the descent of monkeys 

 (in which the lower tusk always remains) from lemurs. 



Another and larger European Tertiary lemur, known as the Adapis, carries the 

 series one step still further back, since it has four premolar teeth on either side of each 

 jaw ; whereas, as we have seen, no living lemur has more than three of these teeth. 

 Here, then, so far as it goes, we have decisive evidence 

 of the approximation of the extinct lemurs to the in- 

 ferior orders of Mammals, among which four premolar 

 teeth are frequently present ; and we may thus hope in 

 time to discover further evidence of intermediate forms. 



Some of the extinct North American lemurs, with 

 four premolars, do indeed exhibit certain transitional THE ^p? UPPER CHEEK-TEETH 

 characteristics ; but it would be beyond the province OF AN EXTINCT EUROPEAN 



of the present work to enter upon their discussion. WJMUROID (Adapts). 



We have already called attention at some length to the importance of these ex- 

 tinct European lemurs as helping to explain the peculiar distribution of their modern 

 relatives ; and we may take leave of the subject by mentioning that their occurrence 

 in France and England during the early part of the Tertiary period indicates the 

 prevalence in these countries of a tropical or subtropical climate. 



