92 Annals of the Carnegie Museum. 



pillar between the two inner crescents of M- in the Princeton speci- 

 men.^- In discussing the differences between the molars of various 

 specimens of Protylopus in the Princeton collection Scott says {I.e., 

 p. 24): "In one case M^ has very small anterior and median external 

 buttresses, and the two outer crescents are of similar size and shape, 

 with equal prominent median ribs. In M- the buttresses are very 

 much larger, and the rib of the postero-external crescent much less 

 prominent than the antero-external one. The buttresses of J\I- 

 are still larger, enclosing small fossettes, and the posterior buttress 

 appears. On M- and M- a small pillar occurs between the two inner 

 crescents." This description answers the condition found in the 

 present specimen, so far as the buttresses of the external crescents 

 and the minute pillars between the internal crescents of M~ and M- go. 

 The absence or presence of the minute pillar on the internal cingulum 

 of M--may well be a variable character. Altogether the Princeton 

 specimen No. 1 1225 might provisionally be regarded as a paratype 

 of Protylopus annectens. The illustration of Protylopus petersoni by 

 Scott {I.e., PI. 2, Fig. 6) does not indicate this bifidity of the inner 

 anterior crescent. 



The fragments of the skeleton furnish no noteworthy characters and 

 add little or nothing to what we already know through the studies of 

 Wortman and Scott. 



The species is interesting from the fact that it furnishes characters, 

 which closely connect Protylopus with Eotylopns Matthew. ^^ From 

 the study of the present material the view expressed by Matthew 

 that Poehrotherium of the Oligocene is probably derived, not from 

 Protylopus of the Uinta, but from some more advanced contemporary 

 genus, is apparently much strengthened. But whether this contem- 

 porary genus will yet be found in the Uinta or a more northern locality 

 is a cjuestion which only the future can decide. 



Measurements. 



Antcro-posterior diameter of superior molar series 27 mm. 



" pi 7 



Transverse " " " 6 



^2 An examination of this Princeton specimen, No. 11225 shows that the teeth 

 are very much worn, so that the inner anterior crescent may or may not be bifid. 

 There is, however, no sign of the minute pillar on the internal cingulum of M ' , in 

 fact the cingulum is rather less developed in the Princeton specimen. 



^^ Bull. Amer. Miis. Nat. Hist., Vol. XXVIII, 1910, p. 41. 



