NO. 8 MAMMALIAN FAUNA, BADWATER AREA — GAZIN 21 



tends posteriorly to a position much farther back than in D. minuscu- 

 lus. The width of the lower teeth is not significantly different but 

 those in the Badwater form are a little shorter, particularly in the pre- 

 molar region. A peculiar parallel with the Desinatotherium line is 

 noted in the anterofx^sterior shortening of the anterior or trigonid por- 

 tion of the premolars, suggesting that the Badwater form is a little 

 more advanced than D. minusculus. This is not an unreasonable sug- 

 gestion since the Washakie horizon represented by the latter, though 

 possibly earlier than Uinta B, is certainly not later. D. minusculus 

 lower teeth, compared in turn with those in Helaletes, are seen to re- 

 semble them very closely. I note only the somewhat more progressive 

 premolars with distinctly more basined talonids, and the presence of a 

 hypoconulid on M3. 



Dilopliodon leotanus, though having lower premolar trigonids short- 

 ened from the Helaletes stage, has these portions developed for the 

 most part about as in Protapirus, not so abbreviated as in Colodon. 

 However, P2 in the D. leotanus specimen at hand is relatively un- 

 developed. Although this tooth shows characters which are probably 

 variable, the paraconid and metaconid are scarcely more than crests, 

 somewhat as in Colodon. Nevertheless, the talonid is more nearly 

 similar to that in Protapirus in that the crest of the hypoconid appears 

 to be more median in position as it approaches the trigonid, produc- 

 ing a rather distinctive labial fold or depression. 



In the lower molars the parastyle development is rather similar to 

 that of Protapirus, although the crosslophs seem more clean-cut. 



Significant features are seen in the upper teeth of the Badwater 

 species, and except for IVP, these teeth were hitherto not known for 

 Dilophodon. It may be noted in particular that P^ and P* ( P^ and P- 

 are not known) have a single, undivided lingual cusp or deuterocone 

 as in Helaletes boops, not divided as in the D esmatotherium-C olodon 

 line, and that in M^ and M^ the metacone, though exhibiting a heavy 

 cingulum externally, is not concave but distinctly convex labially, so 

 that the metacone has a little more conical appearance. Its form, how- 

 ever, is not quite comparable to that in Homagalax or in the middle 

 and upper Eocene isectolophids which, as Hatcher (1896) pointed 

 out, are not entirely suited in this detail as potential ancestors of 

 Protapirus. The form of the metacone is unlike Desmatotherium or 

 Colodon and different than in most of the Helaletes material examined, 

 although in some specimens of the latter the concavity is not empha- 

 sized and much of the Hcptodon material would not be excluded as 

 potentially ancestral. 



