FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 



191 



upheld on present evidence. Aside from the presence of a mesostyle, 

 Deuterogonodon is much less like Phenacodus than is Tetraclaenodon.^^ 

 Dr. Gidley's manuscript notes include two drafts of a description of 

 the type of this genus, in both of which it is referred to Protogonodon. 

 On one, however, almost surely the second, the words "new genus" 

 have later been written under "Protogonodon." Gidley thus came to 

 recognize the clear-cut distinction of this genus from Protogonodon, but 

 his notes do not contain any generic diagnosis 

 or new generic name, and I have been forced to x3% /^i' 



supply these. 



DEUTEROGONODON MONTANUS (Gidley) %mW M 



Figure 44 NSm.- 



a 



Deuterogonodon montanus (Gidley) Simpson, 1935d, p. 233. 



Type.—U.S.'NM. no. 6160, part of right maxilla /0^:f^:'fM 



with a fragment of M^, M^ lacldng the paracone 

 and parastyle, and M'^ complete, mth a left lower 

 jaw fragment, possibly of the same individual and 

 almost surely of the same species, with the talonid u 



of Ml and most of M2. If these should prove not 

 to be one individual, the upper teeth constitute 

 the type, and the lower teeth are a para type. &^ 



Collected by A. C. Silberling. 



Paratype. — U.S.N.M. no. 6161, isolated right Mg. 



Horizon and locality. — All material is from Loc. \ j , / 



25, about 300 feet above the base of Fort Union ^ 



No. 2, Sweetgrass County, Mont. fiqvre n.-Deuterogonodon 



Diagnosis.— Gidley: "Somewhat larger than P. montanus (Gidiey): a, u.s. 



rx^ 7 1 /^ N ,, fi7 N.M. no. 6160, right M»-», 



[Protogonodon] pentacus (Cope). ^^ crown view; b, u.s.n.m. 



Simpson: Sole known species of the genus as °°- ^i*^^- "^^^ ^'' ^"''^^ 



^ view; b', same, internal view. 



denned above. Natural size. 



Measurements are as follows: 



M2 median width 14. 6 



M3 length 10 



M2 (paratype) width 10. 5 



M2 (paratype) length 12. 6 



8' A new species of Protogonodon from the Puerco, which I have described in a note published as a 

 supplement to Matthew's Paleocene Memoir, suggests that within the genus Protogonodon there was a 

 tendency to develop along two different lines, one leading (or related and collateral) to Tetrnctaenodon and 

 one more definitely creodont and ClaenodovAike. If derived from Protogonodon, Deuterogonodon probably 

 arose from a species of the latter, rather than of the former, group. 



8' I quote only enough of Dr. Gidley's diagnosis to establish his authorship of the species. The rest of 

 the diagnosis compares with the Puerco species of Protogonodon and is hence rather generic than specific, 

 end among the few characters given I cannot agree as to the reality or value of some, and others seem to 

 Involve slips of the pen that I cannot correct with any certainty that Dr. Gidley's thought is being followed. 

 The rough manuscript was far from completion. 



