252 BULLETIN 169, UNITED STATES NATIONAL MUSEUM 



Diagnosis— Gidlej'' "P^ to M^^SH- mm; NP-^^lS.l mm; length 

 of M' = 6.4 mm, greatest width=9.1 mm, width across hypocone and 

 metacone=8.3 mm, greatest width of M^=9.8 mm, other measure- 

 ments of this tooth same as those of M^; parastyle and mesostyle 

 prominent, mesostyle angular and continuous with the ectoloph; P^ 

 with uninterrupted internal cingulum, and with low but well-defined 

 lophs connecting the summit of the protocone with the protoconule 

 and base of the metacone respectively." 



Figure 72.— Gidteyina montanensis (Gidley), Princeton Univ. no. 12048, left upper jaw: a, External view; 

 6, crown view. One and one-half times natural size. 



Discussion. — The P^ probably associated with the type is a simple 

 2-rooted tooth with one laterally compressed external cusp, somewhat 

 anterior on the crown, and a small posterointernal expansion of the 

 base but not true protocone. 



My measurements of the type are as follows: P^-IVP, 19.6; M^~^, 

 13.8; length P^, 4.5; width P^, 3.1 ; length P^ 5.9; width P^, 5.8; length 

 PS 5.7; width V\ 7.2; length M', 7.0; width M^, 9.0; length M-, 

 6.9; width M^, 9.9. 



Two other specimens from the same cluster of localities all at about 

 the same level are in the Princeton collection. Princeton no. 14195 

 is an M^ similar to that of the type but slightly larger and with the 

 hypocone more internal. These could be individual variations. 

 Princeton no. 14190 is an isolated P4 7.2 mm in length and 4.8 mm in 

 width. Its size is almost exactly that of the corresponding tooth of 

 ?G. silberlingi, but the protoconid and metaconid are closer to each 

 other and the metaconid is relatively more posterior. 



'* I quote Dr. Gidley's diagnosis from the draft in which he placed the species in a new genus. His other 

 two diagnoses view it as a species of Tetraclaenodon and of Ectocion, respectively, and are therefore inappro- 

 priate. 



