PAL.EOSYOPS LEIDY, AND JTS ALLIES. 
375 
which have the broad and flat V’s so characteristic of Tchuatotherium. The 
external cingnla are a conspicuous feature of the upper teetli in Palceosyops minor. 
Oil all the true molars of P. minor the intermediate tiihercles are much reduced, 
which is sui’ely a Telmatotheroid character. Its superior true molars show alliiiity 
to P. paludosus in the form of molar 3 whose posterior internal angle i.s very 
obliquely cut off, this tooth not having the square form which i.s so characteristic of 
Telmatotlierhmi. Premolar 4 and molar 1 show a considerable difference in size ; 
the superior premolars 1 and 2 show decidedlj^ more affinity in form to the teeth of 
Tehnatotherium than to those of P. paludosus, this especialh’ holding good for the 
first preniolar which is elongated and has the canine-like form .so characterisfic of 
Tehnatotherium. The superior premolars of P. minor .still retain an incomplete 
internal cingulum, which indicates its affinity to Paleeosyops. The external 1o1m>s of 
the premolars in P. minor are decidedly of a Telmatotheroid jiattern having high 
crowns not separated by a buttress and provided with external cingula ; the last 
inferior premolar is moi’e developed in this species than in P. paludosus, as shown 
by the size of the V’s which are plainly marked off in the last tooth of this .scries, 
their connecting crests being large and sharp. This character of their crowns places 
them higher in the scale of development than the teeth of /L paludosus where 
inferior premolar 4 is less developed. The lower molars of P. minor are rather 
more intermediate in character than the upper ones; their crowns are compara- 
tively low ; the posterior tubercle of the last molar is very much degenerated but has 
not reached the cone stage, as the tubercle still retains traces of a valley and lateral 
crest. The V’s of these molars are well expressed and their crests inoix* sharply defined 
than in P. paludosus. The dental characters of P. ininor, therefore, indicate that 
this species holds an intermediate position between tyjjical P. paludosus and Tclnta- 
tothcrium, although I think it is probable that P. ininor was dei-ived from P. palu- 
dosus, or may have arisen directly from P. borealis, in the latter ca.se dmxdoping 
parallel wdth Tehnatotherium and not leading directly to it. a view rend.ux-d prnl>- 
able bv its small size. It is, how'ever, more probable that P. vallidcus and certain 
varieties of P. paludosus are the direct transition forms lx>tween tlie latter and 
Tehnatotherium. The characters of the lower molars of P. longirostris prove that 
this species is closely related to P. minor. 
If I had followed strictly the chronological appearance of the si)ecies of Paheo- 
syops I should have been forced to consider P. borealis first, but as the idiarae- 
ters of the teeth in this species more strongly resemble in my opinion, tho.'s- of 
Telmatotherium than those of Palceosyops, I shall therefore deviati* fnan the ordin- 
ary arrangement which I have followed and consider the characters of /’. borealis 
here. The first superior molar of this species reminds one strongly in its gimcral form 
of that tooth in the genus Telmatotherium. It is square with rather broad external 
V’s, the latter being shallow and broad as in Telmatotherium. The pn)toconulcs of 
molars 1 and 2 are small. In the first molar the posterior intennediafe is wanting, 
or rather the slight ridge developed on the posterior j)art of this t<H)th is the 
