4 
1884.] The Condylarthra. 795 
or s . . . 
Superior molars with an external cingular cusp ;`inferior premolars without internal 
ORD Som ET Py conus. 
ledge 
x cto 
o supplementary external cusps, inferior iata with ‘lena Jedgea: “Poripiyclns. 
I 
IL. aia tubercles wanting; four inferior premolars, without internal 
Su 
perior molars with posterior mes cusp only, besides internal V; last two 
superior premolars with internal lobes ......---++++> «o o o Anisonchus. 
Superior molars with internal V mik: no other interhal lobëš; ; á two superior 
se premolars with internal cuspS.........seeeeeeeseeeeee i ‘emithleus 
perior molars with posterior internal es only, haika apex of V; fourth supe- 
rior premolar only with internal lobe.........-- Haploconus. 
ir oo ee 
Superior molars unknown ; inferior eae No. Iv ? with two opposed 
crescents and a heel. 
Inferi : 
nferior molars with one or two pairs of opposed crescents...eess-+++++ 
All t . ; 
| he known species of the Periptychide are from the beds 
the Puerco Eocene. 
From 
the preceding table it is obvious that the yeeie of this 
iÍ ea) y : 
- 
D 
ee e q 
m pes Puerco beds of 
o. from below. 
é A ¢, distal end 
U. S. Geol. Survey 
Fic. 2. 
New al sag mg molestus Cope, two-thirds natural size, = 
Fig, 4, sieht ci 1g. ay right maxi ary bone, externa view ; 
of ‘ mus mandibuli, — ge 6’, do. from ahs 
V. Ha ayden i in charge. 
sly presen considerable diversity in the degree of complica- 
or less sj w molar teeth. In all of them the premolars are more 
while in S e, and in Hexodon they are but three in number, 
In Hex paged genera there are four. 
of the d odon Cope the type is most deve 
ental prehension. With the shortening of the jaws c 
loped in the direction 
omes 
