37J 
A MKMOIR UroN TJIE GENUS 
, . i- .1 which occurs in no otlier species of the group 
.Uvi.l.-.l cluinu-t 4 -r ol this loriii a molars of well developed interinediiiU- 
w the ptvM-m-f on tlie ,idges connecting the external V’s with 
.•.iiiulcH wliile then- are nu phettacodus and Hyracotheritim the 
the internal cones. In such pit n cones, and I conclude that this 
, . il::, "primitive thm. iu the Pal.osyop,, 
111!.. ,le)!eiienite.l ; this is a spoclillization ill the latter 
liii. wlii'r. i..l.l.p.»l fertile ireiierii Tel,mtoll,eriu,n an. D.plawdou I he reteii- 
li.:;,' I'ft l»e< s"|H'rier pieiiielar of L. laluep. iiidieii es its |nniii- 
character while the anterior external median nb is also prominent Ihc fact 
that in /.. hticeps the e.xternal 1oIk-s of tl.e last superior preniolar are Hubc-<,ual may 
iM- n-ganhsl as a s|HH-iali/aMl rather than as a primitive character. 1 consider Limn^ 
/o,.th,a/is as .,nite a highly specialized member of the genus liecaust- the 
nietanaiules of the true molars have been lost, and the crowns ot the molars 
an- .sanpamtivelv much liigher than in the less specialized species ol the genus, 
while the ext«-rnal Vs in L. /ou/ina/is mv wider, and in some respects have taken 
on a iiion- strongly Telniatotlieroi*! facies. The greater .size of the protocoiie of molar 
I in L/onthm/is as coiiipan-d with the hypocone is a primitive character, tlie liyjM)- 
4-one a|i|M-nring as if it had Is-en just added. 
I n-ganl Pn/trosyops paludosus as decidedly* the most primitive menilx-r ui 
the p'lnis in its dental charactei-s, and it is ])articularly fortunate that such is tlie 
eniM- ns the material referalile to this species in the Princeton collection is the most 
nhundniit, so that 1 am eiiahh-d t<» point out the central form, as it weiv, of this 
s|M-«’ies. and to indicate a numiH-r of interesting transitional varieties whicli an* 
gn>u|s<<l nnaind it and liave charai-tei's iiointiiig tow'ard Limtiohyops and Tclmato- 
thfrium n-s|MH-tively. Thesi- varieties of P. pahtdostis illustrate how clo.sely the 
g«-neni an- ls»iiml togetlu-r by transitional forms. In typical P. paludosus the 
incisors an- of n etuiical form without the basal cingula which is so characteristic of 
theiM- tt-eth in 7'clnuitoflienum. The canines are large, conical, round in section, 
and an- not pmvided with strong cutting ridges. The upper and low er molar series 
«»f /*. paludosus have very low and undifferentiated crowns. The superior- pivmolar 
without the anterior and po.sterior heels pre.sent in 'Peltualothcr- 
i-oing neail.v ..q„.,l i„ trunsvem. 
Tl... lir,. I„,v..r pr,.,„„|„r „r />. ,, , 
