3S3 
PALiEOSYOPS LEIDY, AND ITS ALLIES. 
Conclusions. 
The foregoing study of the relationship of the niemljers of thi.s sulifamily lead 
to the following conclusions as to their phylogeny : — 
1. That Lambdotherimn may be the ancestor of the Pala?osyop.s-Diplacodon 
line, although certain specialized characters of its dentition, the loss of tlie first 
inferior premolar and the more complex development of its inferior preniolar 3 
indicate that Lambdotherimn leads to a side line. 
2. Palceosyops borealis appears to lead to a side line, perhaps to P. minor. The 
molars of P. borealis point to this conclusion because of their close ivsemblance to 
those of Peb7tatotherium. 
3. I consider that Lmi7tohyops laticeps is the most primitive memlx'r of this 
group from the Bridger, because of its low form of molar, with large intermediate 
tubercles, and its last superior molar has two internal cones. The form of 
the less specialized skull of L. laticeps^ with short premaxilhiries and much elong- 
ated nasals, points to the primitive position of that species. From such a form I 
believe P. Icevide7is has arisen, that species being intermediate between L. laticeps 
and P. paludosns. 
4. P. paludosus has arisen from L. laticeps through the intervention of P. 
I(evide7is ; in the latter the simplification of its superior premolar 2 is greater than 
in P. pahtdosns. 
5. P. vallide7is has developed from P. paludosics by lengthening and increasing 
the height of its molars. 
6. Tel77iatotherui77t C7dt7'ide7is has originated by increase in height of theemwns 
of the molars and widening of the external V’s, and a reduction of the intenuediate 
tubercles of P. paludosus. P. vallidens is the transition form Ixdween these two 
species. 
7. T. C 7 dt 7 'ide 7 is, on account of the simpler structure of its superior pu-molar 2. 
is the most primitive member of the genus Tel77iatothcrmm, and was the ancestor of 
T. validns. 
8. By lengthening of the jaw symphysis of T. validns, with a concom- 
itant widening of its diastema, T. /lyogfiatJms has arisen. 
9. I regard L.fo 7 iti 7 ialis and P. megarhhms as siiecialized fonns and not in the 
direct line of descent leading to Tel7)7atotherin7n. 
10. As already mentioned several times in this memoir 1 consider that Tcl77ta- 
totherhmi is the most highly specialized genus of the Palceosyopi/ier, aiipmaching 
more closely in its dental characters to Diplacodon than any other genus of the sul>- 
family. TePiatotherumi should, therefore, hold an intermediate position Ixdwwn 
Palceosyops and Diplacodo7t. 
The accompanying phylogenetic table will make clear the suppo-sed relation- 
ships between the species of this subfamily. 
