318 
A MEMOIR UPON THE GENUS 
first have well-marked internal lobes (although in Cope’s figure of this species the 
internal lobe of superior premolar 2 is omitted), and their internal basal cingula are 
incomplete. The last premolar is considerably smaller transversely than molar 
1. In this character it differs from P. minor where these two teeth are more 
nearly of the same dimensions. The measurements of the molar series are 
mucli less than in P. pahidosus or L. laticeps. The crowns of the molars are low, 
without external cingula; the buttresses are well developed, the anterior is pro- 
longed, the median buttress being of the typical Palmosyops form ; that is to say, not 
widely constricted ofli 
In its molar characters P. Icevidens differs very much fi'om P. minor, in which 
the crowns of the molars are high, with prominent external cingula. The interme- 
diate collides are reduced. As Cope' says “ The anterior median small tubercle of 
the first true molar is wanting”. This is a character very different from that of 
P. paludosus where the protoconules of the superior molars are always very large. 
The internal cones of the molars are low, and in the last superior molar the posterior 
internal angle has quite a large basal enlargement. This portion of the tooth is 
damaged, but I think it points to the fact that we are here dealing with another 
species in which a rudimentary hypocone is present on the last ujiper molar. 
Prof Cope“ figures another series of molars which he supposes to belong to this 
species. Their dimensions are intermediate between those of P. Icevidens and P. 
paludosus. These teeth ai'e no smaller than some molars which we have referred 
to P. paludosus in the Princeton collection, so 1 think they should be referred to 
that species. The last preniolar of the above mentioned series has its external lobes 
without a trace of a median buttress. This is a character which is variable in P. 
paludosus, but is generally present. The intermediate conules in the above men- 
tioned molars are well developed, and the last preniolar is smaller than the first tiaie 
molar transversely. In both series of molars described by Cope as belonging to this 
species the enamel is smooth. 
Shdl (Fig. 2, p. 289). — The facial region of the skull of this species in Prof 
Cope’s collection is very finely preserved ; it is rather short and, when compared 
with this region in the skull of P. paludosus, is much higher and more compressed. 
This is especially noticeable in the height of the roof of the skull above the pre- 
molars. The nasals are much elongated, narrow and not expanded distally. 
The characters of the nasals are nearly the same of those of L. laticeps. 
The nasal notch is deep; its superior border slopes gradually downward, but 
the inferior, instead of being nearly parallel with the superior, diverges widely 
from it and thus makes the anterior narial opening very large. The iireniaxillaries 
are much elongated from above downward, and sliort antero-posteriorlj-. Their 
symphysis is filled up by a matrix in this skull, although Prof Cope considers that 
there was no union between these bones. This would be an exception to the rule 
'Tertiary Vertebrata, page 703. 
^Tertiary Vertebrata, PL L, fig. 3. 
