20 



MR. R. I. POCOCK ON THE EXTERNAL 



on Tarsias, Van der Hoeven's on Perodicticus, Huxley's on 

 Arctocebus, Beddard's on Hapalemur, and so forth. 



Many of the facts dealt with in the following pages are 

 of course well known. Some characters, however, are here 

 described, I believe, for the first time; and I trust that the 

 collation of the facts and their comparative treatment may prove 

 useful to future students of this group. 



In the matter of names I have followed the conservative course 

 of using Lemur for the species to which it has been by common 

 consent assigned in all recent literature, although by the rules 

 of nomenclature, it has no right to a place in the Primates 

 at all, but belongs by Storr's very definite selection to the 

 Dermoptera, Galeopithecus volans being its type-species. Even if 

 that selection be set aside, it appears to me that the " indications" 

 of the 10th edition of the 1 Systema' show that the species known 

 as Lor is tardigradus is its type. This is clearly a case for the 

 " Fiat " Committee on Mammalian generic names ; and it is my 

 confidence that the Committee will see the wisdom of allowing 

 Lemur catta to stand as the type of Lemur, that induces me 

 to retain this generic name in its commonly accepted sense- 

 Similarly I have employed Chiromys for the Aye- Aye (mada- 

 gascariensis), although Daubentonia is the correct title for that 

 species. The Fiat Committee, 1 believe, has these names now 

 under consideration. 



The Muzzle and the Rhinarium. 



The bestial aspect of the face of the Lemuroid as compared 

 with the Pithecoid Primates is not due to the general elongation 

 of the jaws. In this character the Lemurs are surpassed by 

 Papio amongst the Pithecoids. It is due to two correlated 

 features, namely, the retention of the primitive moist glandular 

 rhinarium and the projection of the upper jaw supporting it 

 beyond the level of the chin. 



The rhinarium is naked to a varying extent on its dorsal side 

 and .also beneath the nostrils laterally and in front. It is con- 

 tinued downwards in front as a strip of grooved naked skin 

 cleaving the upper lip to its inferior edge. At this point the lip 

 is adherent to the gum covering the premaxillse, so that it is 

 incapable of protrusion. 



Although the rhinarium is tolerably similar throughout the 

 group, one or two variations may be pointed out. In the typical 

 Mascarene Lemurs, including Chirogaleus (text-fig. 1, A), the labial 

 extension of the rhinarium is comparatively short and the later- 

 ally extended infranarial portions shallow. In Perodicticus the 

 infranarial portion is deeper ; but in Nycticebus it is not so. In 

 Galago crassicaudatus (tex^t-fig. 1, B) the labial extension of the 

 rhinarium is <*a little longer and thinner than in Chirogaleus 

 and Lemur. In Ilemigalago demidoffi it is remarkably long and 

 gradually widens above where it passes into the infranarial portion 



