PAL.EOSYOPS LEIDY, AND ITS ALLIES. 
373 
ill the latter geiuis; that is to say, the second has its protocoiiid uiiudi siiialler and 
the fourth has its V’s less well developed. In P. palndosns, as in all the other 
species, the inferior premolar 2 appears to be less highly develojied than in the 
genus Lambdotherium, where in some species a well marked rudimentary metaconitl 
is present on premolar 2. The crowns of the superior true molars of P. paludosus 
are very brachydont and the external A^’s are much rounder and narrower 
than in Pelmatotheriuni^ while the external face of the molars is totally without a 
cingulum. A primitive character of the upper molar series of P. paludosus is the 
presence of a large anterior intermediate coniile on each true molar. Tlie pmto- 
conules are well developed in P. paludosus and gradually Ix-come rudimentary in 
some of the smaller species of Telmatothcrium. In the most jjriinitive up|K*r 
molar oi P. paludosus m the collection (lO.OO!) A), the external \ s are narrow 
and each one is provided with a prominent vertical rib. which I take to Ik* the 
remains of the convex external snrface of the bunodont cone from which, by the 
coalescence of the latter, the external A"’s of this type of molar have iK-eii derived. 
The median buttress in this molar is very low and undeveloped. Another primitive 
character of the tooth is the presence of both the intermediate connles, the anterior 
being connected by a Avell marked ridge with the anterior cingulum. 'I'he inlerior 
molars of P. paludosus have their \'’s much lower and their civsts less well devel- 
oped than in Telmatotheriu7n . There are no traces of any posterior intermediate 
connles on the inferior molars 1 and 2 of this species. 
I believe the last inferior molar of P. paludosus has its posterior tulK*rele 
highly specialized because in the supposed ancestor of PaUcosyops ( Latubdolher- 
ium) the posterior tubercle of molar 3 is an open lobe and not a cone. This is als4i 
the case in a less specialized form like Hyracollierium. the bunodont char- 
acter of the loAver molars is strongly preserved. In the latter genus the |H»sterior 
tubercle is less specialized than in Lambdotlicnuvi. It consists merely of 
an open semicircle with its arms running to the external ami int<*rnal face of 
the molar. In La^nbdothet'ium, on the other hand, this tniK-rcle has a.>»snmed^ 
a more specialized character ; it has become more constricted off from the IkmU- (.f 
the tooth by the external crest of the tubercle becoming no longer eontimions with 
the external border of the tooth, and by running inward its internal crest has Is'cmue 
continuous Avitli the entoconid. In most of the i)osterior and inferior mohu-s of the 
species of this subfamily such is the condition of this tulKU-cle, but in P. paludosus 
and some of its varieties the crests and valleys have become aln.rted and the 
orio-inal open and functional lobe has degenerated to a mere cone. 
° The first variety of P. paludosus which I shall describe is a iK)rtmn <d a skull. 
No. 10,276, from the Bridger proper, in the Princeton collection. It contains a part 
of the’ mo’lar series, and on one side the last tAvo uppr molars. The total 
dimensions of these teeth are considerably less than in the typical form; their 
enamel is smooth with reduced intermediate tubercles. A very mtei-estmg h*atun* 
in the last molar of this skull is that its posterior internal cingulum has lus,*d with a 
