176 DE. Or. ELLIOT SMITH ON THE BEAIN 



teaching of Hubrecht, the approximation of Tarsius to the Apes does not sever its 

 even closer bond of affinity to the Lemurs. In all the Prosimise the constitution and 

 grouping of the furrows of the neopallium are distinctly and unquestionably Primate: 

 in no other mammals (with the possible exception of some of the Edentata) do we find 

 a true Sylvian fissure; in no others (excepting possibly some primitive Carnivores) do we 

 find the distinctive type of calcarine sulcus that occurs in both Lemurs and Apes : in 

 no other group of mammals does a properly constituted central sulcus of the true 

 pithecoid type tend to make its appearance, as it does in such diverse families as 

 the Lorisinee (Peroc?^c^^c^«s)5 Indrisinse (sometimes in Projjitheciis), naA in Chiromys 

 among the Prosimise : and turning to the evidence of the cerebellum we find in such a 

 series as Propithecus, Lemur, Loris, Tarsius, and Ilapale a complete bridge between 

 the Lemurs and the Apes. 



Conclusions. 



L The brain oi Lemur jullyi closely resembles that of the existing members of the 

 genus and especially the species varius, most of the differences that are found being 

 explicable by the larger size of the extinct animal's brain. 



2. The brain of Mesopropithecus pithecoides is an almost exact replica of that of 

 Indris. 



3. In the only features in which these two brains differ from those of their nearest 

 living relatives they approach one another's type, as well as that of other Prosimian 

 families, and to this extent can be said to be more primitive. 



4. Neither brain can be said to be more pithecoid than those of their living 

 relatives. 



5. The \)X&\Q.oiNesopitliecus\_GloUlemur'\ presents undoubted affinities to the Indrisine 

 type. There is no feature or combination of characters which can be said to render 

 this brain any more pithecoid than that of any other member of the Indrisinge. 



6. The brain of Palceopropithecus maximus is distinctly Indrisine. It exhibits an 

 early stage of those retrogressive changes which we recognise in their ultimate and 

 somewhat diversely specialised forms in the brains of Chiromys and Megaladapis. 



7. Although Chiromys does not show any trace of the disintegration of the lateral 

 sulcus, which is so characteristic of the IndrisiuEe, it is linked by so many striking bonds 

 of affinity to Palceopropithecus that it is impossible to separate them the one from 

 the other or from the Indrisinse. 



8. So far as the evidence of brain-anatomy is concerned we must regard Propithecus, 

 Avahis, Indris, Mesopropithecus, Nesopithecus, Palmopropithecus, Chiromys, and Mega- 

 ladapis as the diversely specialised members of one family, all of which exhibit 

 in greater or less degree distinct evidence of retrogressive changes from a more primitive 

 (and also more pithecoid) type. 



