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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 83 



Diagnosis. — Molars about as long as in T. symbolicus, but markedly 

 narrower. Crenulation slight. Paraconid vestigial, trigonid broadly 

 basined with crenulated anterior margin. External cingulum absent. 

 M2 length 7.7 mm, A\ddth 6.2 mm. Ratio trigonid width: talonid 

 width M2 1.13. This species may belong to Gidleyina (infra). 



GIDLEYINA, new genus " 



Type. — G. montanensis Gidley, new species. 



Distribution. — Paleocene, Fort Union, Mont. 



Diagnosis. — Closely resembling Ectocion, but upper premolars 

 with much smaller metacones, first and second molars with smaller 

 mesostyles and hypocones, protoconules of P^"* and M^~^ slightly more 

 united by lophs to protocone. Among Middle Paleocene genera 

 closest to Protoselene, but sharply distinguished by large postero- 

 internal protocone on P^, distinct conules on P*, and other details. 



GIDLEYINA MONTANENSIS Gidley, new species, ex ms. 



Type. — Princeton no. 12048, part of left maxilla with P^-M^ and a 

 probably associated right P^. 



Horizon and locality. — Locality 68, about 1,000 feet above Gidley 

 Quarry, Fort Union, Crazy Mountain Field, Mont. 



Diagnosis. — Gidley: ^^ "Parastyle and mesostyle prominent, meso- 

 style angular and continuous with the ectoloph; P^ with internal 

 cingulum and with low but well-defined lophs connecting the summit 

 of the protocone with the protoconule and base of the metacone, 

 respectively." 



Simpson : Measurements in millimeters as follows : 



7GIDLEYINA SILBERLINGI Gidley, new species, ex ms." 



Type. —V.S.N.M. no. 6166, partial left lower jaw with P3-M3. 

 [Three other fragments are included in the same lot and probably are 



** In one draft of Gidley's notes the genotype is referred to Euprotogonia, in anotlier to Ectocion, and in 

 another to a new genus. Even supposing the last to be his latest opinion, as it probably was, I cannot 

 validate Oidley's authorship of the genus as the name he uses is preoccupied. It is appropriate that a genus 

 that he recognized and one of the most important in the collection that he worked on for so long should be 

 named for Dr. Gidley. (Gidleya Cossman, 1907, is a fossil bovid.) 



« Much of the diagnosis consists of measurements, which I replace with new figures. 



<' This species was at first referred to Euprologonia and then to Ectocion by Qidley. Probably he finally 

 recognized its probable pertinence to the genus I have called Qidleyina, but this does not appear in his notes. 

 Only enough of his diagnosis is quoted to validate his authorship of the species; it is based on reference to 

 Euprotogonia [Tetraclaenodon] and is therefore not fully apropos. 



