436 Bulletin American Museum of Natural History. [Vol. XXXIV, 
Key to Species of Pelycodus. 
I. Paraconids distinct on mi-3 
1. Mi3;=11-14 mm. Upper molars trigonal to sub-quadrate; no hypocones 
P. ralstont. 
II. Paraconids vestigial on me_3, distinct on mi 
2. M.i-3=14-16mm. No hypocone on upper molars, inner cusp of py weak 
P. trigonodus. 
3. M,-3=14-16 mm. Hypocone on m!~, obscure to distinct, inner cusp of 
Du STON fog heey aka bine Sk OE eae oN SA eee aek wlan at yaion ee gM P. frugworus. 
4. M,-;=16-18 mm. Hypocone on m!'~, obscure to distinct, inner cusp of 
Lee ie a ree te ee eo hee eee Ce Seb ance P. jarrovit. 
III. Entoconid placed more anteriorly than in other species and connected by a 
crest with metaconid. 
We Nis we Pas Pret a tv Kid er wo 6 Ch gee Pk US See rer 7 tutus. 
Pelycodus ralstoni sp. nov. 
Type, No. 16089, upper jaw with p‘-m’, from Sand Coulée zone (basal Wasatch) 
in Clark Fork basin, Wyoming. 
Distinctive characters: M,.3=11-14 mm. p, smaller 
and less compressed than in P. trigonodus; upper molars 
more triangular, of less anteroposterior length. 
This species is considerably smaller than the 
others, the anteroposterior diameters of the teeth 
notably less, the premolars smaller in proportion. 
The protocone is not broadened posteriorly as it 
is in P. trigonodus. | 
- Some thirty specimens from the Sand Coulée 
beds in Clark Fork basin agree more or less ex- 
actly with the type. A dozen specimens from 
ee ae diany. Shoshone River and a few from other localities 
upper jaw, external and low down in the Gray Bull also belong here. A 
crown views. Type speci- few are intermediate between P. ralstoni and P. 
men, Sand Coulée beds, : 
Clark Fork basin, Wyoming. trigonodus. 
Pelycodus trigonodus sp. nov. 
Type, No. 15017, upper and lower jaws, from the lower part of the ey: Bull 
horizon, 5 miles south of Otto, Wyoming. 
Distinctive characters: Mi.3=15 mm. No hypocone on upper Or em P, with 
small metaconid, more compressed than in P. frugivorus. 
