PALJ^OSYOPS LEIDY, AND ITS ALLIES. . 317 
close affinity to that of Telmatotheriimi in its high form, whereas in P. paludosus 
this tooth is generally very hroad and low, although we have one jaw oi P. palu- 
dosus in the collection in which it is quite elongated and narrow. I have con- 
sidered the latter variety as a transition form between P. paludosus and the species 
under consideration. 
d . vallidens is surely the direct transition form to Pelniatotherium ; so we have 
in the three species, viz : P. paludosus with its varieties, P. vallidens with its transi- 
tion form of molar, and lastly in T. mltridens, the final differentiation of the pos- 
terior tubercle, which in the latter species has assumed the form of a true lobe, 
with a ^rell-marked valley and crests. The open form of tubercle in Telmato- 
thertuni must be considered a case of reversion. 
Lower Jaw. — The shape of the jaw in this species is very much like that of 
Telniatotim'ium ; it is much elongated and very deep. The anterior portion of the 
horizontal ramus narrows more abruptly than does that of P. paludosus. 
The body of the jaw is thinner than in P. paludosus and its j)osterior 
border is nearly straight and does not show the middle convexity and pos- 
terior concavity so characteristic of the mandible in the latter. The posterior 
inferior portion of the jaw is not strongly inflected as in the last named species. 
The angle of the jaw in this specimen is wanting. The coronoid 23 rocess is 
high and slender — much higher than the condyle. The region of the sym- 
physis is more procumbent than in P. paludosus. The dental foramen is 
large, ])laced anterior to the median line of the ascending ramus and on a line 
with the molars. The mental foramen is large and placed below the second 
premolar. From the consideration of the characters of this jaw we see that 
this species was more closely, related to Telmatotherium validus than to P. paludostis. 
PALiKOSYOPS L.EVinEXS. 
(Not 1\ paluihmi.H Leidj’.) 
Prof Cope' has established this species upon the characters of a fine skull in 
his collection. He considers this species probably equal to Leidy’s smaller form — our 
P. minor ; but in this identification I cannot agree. I shall point out later the dif- 
ferences in the dental characters of these two species. In some respects the 
characters of the skull of P. leevidens, like those of the teeth, approach closely 
those of L. laticcps. 
Dentition. — The dentition is interesting as it is very closely related to that of 
Limnohyops laticcps, and I consider the molar characters of P. Icevidens much inore 
closely related to that sjsecies than to P. minor. 
The fact that the second superior premolar has only one external lobe is unique, 
and upon this character Coj^e has established the species. In the dimensions of its 
teeth P. Icevidcns a2:)25roaches more closely P. minor. The characters of the 
incisors are tyjjical of the genus, viz : rounded cones without cingular bases. Both 
the pre- and postcanine diastemas are very small. All the preniolars except the 
'Annual Keport tJ. S. Geol. Surv. Terr., 1872 (1873) p. 591. 
