ON STJBFOSSIL PEIMATES FROM MADAGASCAE. 161 



characters are present to a greater or less extent among the Platyrrhine Monkeys. No 

 doubt a more extensive survey would reveal other examples. 



Such a diagram cannot be more than approximately accurate, but at any rate it is 

 very evident that it is quite impossible on the strength of the characters here enume- 

 rated to draw any dividing-line between the two " sub-orders." 



Some of the facts adduced by Dr. Elliot Smith in his memoir on the brain-casts of 

 Mesopropithecus, Paheopropitliecus, and Lemur majori seem to me strongly to confirm 

 the views advanced in the foregoing sections. That the brain of Perodicticus, for 

 instance, should reproduce almost exactly the furrow-pattern of a genus of Cebidte 

 appears a fact of extraordinary interest when we realise that possibly the whole of 

 the Tertiary and Recent geological epochs have intervened since the -divergence of 

 the stem.s which gave rise to these widely-separated genera. That this is no chance 

 resemblance seems also confirmed by the further statement of Dr. Elliot Smith that the 

 histology of the brain-cortex of the Lemurs and Apes shows a complete bridge of 

 transitional forms between the two " sub-orders." 



It must be remembered that the real relationships of many of the genera of the 

 Lemuridse outside of Madagascar are probably much disguised by the adoption of a 

 nocturnal mode of life. The extraordinary development of the orbits of Tarsius 

 resulting from this cause seems to have modified the shape of the whole anterior 

 part of the brain-case. The strangely flattened skull and everted upturned orbits of 

 some of the Lorisinae recalling the Eocene Prosimise is again probably largely a 

 secondarily acquired condition depending on their mode of life. This seeming reversion 

 by specialisation and retrogression to a lower and more primitive type is well seen in 

 Megaladapis and Palceopropitliecus. 



The facts and considerations adduced in this memoir together with the results 

 arrived at by Drs. Forsyth Major and Elliot Smith as the outcome of similar comparative 

 study, seem to me to warrant our arriving at the following conclusions :— 



General Conclusions concekning the Relationships op the Lemurs. 

 1. The recent Indrisinas, Chiromys, MesoprojnthecKs, Palceopropithecus, Archceolemur, 

 and Hadropithecus, are all more or less specialised representatives of one common 

 Primate stock. These related genera may be conveniently grouped in one family — the 

 Indrisidse. 



Text-fig. 52 (p. 160). — Diagram showing how many of the so-called distinguishing features of the Lemurs fail, when applied 

 as differentiating characters, to distinguish between the two "sub-orders" of Lemiiroidea and Anthropoidea, The ratio 

 of the black to the tinted area in the small squares represents approximately the extent to which " Anthropoid " and 

 " Lemuroid" characters respectively are present in the genera named at the head of the Tertical columns. The reference 

 numbers in the two right-hand columns indicate some of the various genera or species of Monkej'S in which so-called 

 Lemuroid characters may be observed, viz.: — 1. Mycetes; 2. Kyctipithectis ; 3. Alouatta; 4. Piihecia, C'ebws, Mycetes; 

 5. Mycetes; 6. Chrysothrix ; 7. Fitheda, Jacchus; 8. Mycetes; 9. Cebidis, Hapalida ; 10. Cebid(S,Hapalidts; II. Pttkecia 

 Nyctipithecus, Brachyteles ; 12. Piihecia, Jacchis, S;c. ; 13, 14. Papio. (This list is by no means exhaustive.) 



Note. — The validity of this comparative survey is independent of Ibe question whether the pithecoid features of tlie 

 Malagasy Lemurs are ancestral or acquired by " convergence." 



