PHYLOGENETIC SUMMARY 439 



PHYLOGENETIC SUMMARY 



Xearlv all known gen-ra of recent and fossil leiuuroids have been 

 studied by tlie writer v. itli sjiecial reference to the basicranial region, 

 dentition, and limbs. It is proposed to divide the suborder Lemuroidea 

 into three major groups or series — the Lemuriformes, the Lorisiformes, 

 and the Tarsiiformes. 



Of the Lemuriformes, bv far the most ])rimitive is the subfamily 

 Notharctinffi of the family Adapida?. This subfamily first appears as 

 small insectivorous forms of the genus Peh/codus in the Lower Eocene 

 of North America. These have the primitive dental formula of 



2 14 3 



I — ' C— ' P— ' M— and siiiir)le ti'ituhercular molars. The next stage, A"o- 

 z 1 4 3 



flmictus-. with ((uadrituhercular molar teeth, is well known in the skull and 



most j)arts of the skeleton. The sul)family terminates in the relatively 



large and piogressive genus TeJniah'sles of the Tapper Bridger formation. 



Kxcept for cei'tain details of the molars, the Xotharctinjie appear to be 



sli iicturaliy ancestral to all the higher Lemuriformes. 



Ill iMirope the true Adapiiue are said to appear in the upper levels of 

 the Lower Eocene, but are moi'e abundant in the ^[iddle and L^pper 

 Eocene. The Ada])ina' aie closely related to the earliest Notharctinae, 

 bat rollew' a diifei'ent tiend of evolution of the molars. The best known 

 genus. Adiijiis, is evidently a s])ecialized side branch; lint Pronycticehus 

 (Trandidiei', whieli. in tln' \\i-itei'"s judgnieid. sliould be referred to the 

 Adapiiiie, has tlie expected charactt'i-s of the hasicranium, dentition, and 

 general skull chai'acters for an ancestor of ihi' lemurs of Madagascar. 



The laltei' constitute all the existing blanches of the Leinnri foi'ines 

 and include three families — the Lemurida', the Indrisida?, and the Cbii-o- 

 myida-. These three families seem to ha\e sprung from a common stock 

 which eiilerecl .Madagascar perhaps in Oligocene times. The earliest 

 ti'ue leiiiiirs prohably liiid ;i fairly sIkh'I face and large orbits, a wide 

 basicraniiini and expaiideil hidhe: the upper molars mav lunc heen lil<e 

 those of I'roni/rl II chiis. namely. 1 rit ultercu la r, with a |)roiiiineiil cingii- 

 lum-hypocoiie : ihr lower incisors and canines were partly procumbent, 

 pill' and pin, were small or aliseiit, the jaw was fairly siiort and deep 

 with a large angle. Clieiroi/d/nis of the mouse lemurs has retained most 

 of these |)riiiiili\e characters. 



'I'lie varied descendants of this relatively high type exhibit diver.se 

 (omliinat ions of ictrogressixc and progressive changes. 



In Mc(/(il(i(f(i/tis, for example, there was an extremely rapid increase 

 in size of body and in the length hoth of the face and of the brain-ca,so. 



