PEIMATES PEOM MADAGASCAR. 83 



tri-tubercular form ; indeed the condition of the molars in some of the Lemurin^ 

 which have a strong postero-internal cingulum does not materially differ from that seen 

 in Palceo2)ropitheciiS. The transverse ridge joining the posterior labial cusp with the 

 hinder edge of the anterior lingual cusp in the first molars of Projnthecus is traceable 

 in Palasoprojiithecus. The third molar of the fossil genus is greatly reduced, the two 

 outer cusps having quite disappeared and being represented by a line of small nodules ; 

 the inner posterior cusp has also gone in most specimens. The series of the premolars 

 and first and second molars form nearly straight lines which converge but little towards 

 the anterior part of the palate. 



The appended table (p. 86) gives the dimensions of the teeth of a series of skulls. 

 It will be seen that considerable variations occur, as might be expected from the great 

 diversity in the size and proportions of the skulls themselves. The teeth of the lower 

 jaw of Palceopropithecus ingens have been described by Dr. Grandidier, and these agree 

 so closely with the larger species that it does not seem necessary to describe them 

 minutely again. The annexed tables (pp. 84-85), giving detailed measurements of a 

 series of skulls and mandibles, will serve to supplement tlie foregoing description. 



Genus Mesopropithecus (Standing). 



Definition. — Subfossil Indrisinse retaining many pithecoid features. Brain-case 

 rounded, and showing constriction of postorbital frontal region. Sagittal and 

 lambdoidal crests generally present. Interorbital frontal region elevated, with steep 

 facial angle. Orbits small and forwardly directed. Postorbital bar triangular in 

 section. Nasals short and broad. Zygomata high and arched. Palate broad. 

 Series of molars and premolars parallel. Mandible massive, with inclined symphysis. 

 Auditory bullae prominent. 



T~v ^ ^ r 1 i. 2 : c. 1 : pin. 2: m. 3 



Dental formula : i. 2: e.O: pm.2: m. 3 - 



Mesopropithecus pithecoides (Standing). (Plates XXI.-XXIII.) 



Among the Lemuroid remains in the collection of the Academie Malgache are 

 four skulls which, while agreeing in many respects with the existing genera of the 

 subfamily of Indrisinse, diff'er from these latter in so many important particulars that 

 they must be referred to a new genus. To this I have given the name oi Mesopro- 

 pithecus. All the four skulls belong to a single species, which I propose to call 

 pithecoides. 



As this specific name implies, the new genus presents certain well-marked pithecoid 

 characters. While agreeing in the main with the recent Indrisinse, it shows also 

 many striking resemblances to Archceolenmr (Nesojnthecus). Its main interest indeed 

 lies in the fact that it definitely connects the Archaeolemurs with the Indrisinse, and 

 hence throws a clear light on the origin of the modern genera of this subfamily. 



VOL. XVIII. — PART II. No. 4. — May, 1908, jf 



