31 
DISCUSSION 
Taxonomy of Eodelpkis. In no way does this new specimen differ 
sufficiently from the type of E. cutleri to permit any taxonomic distinction. 
Matthew’s description of E. browni differs from the details given above 
chiefly as follows: 
( 1 ) He states that second and third molars are similar in size (both 
are worn and corroded). 
(2) The paraconid and metaconid of Ms are said to be apparently 
of equal height and the protoconid lower than either (inferred from bases 
of broken cusps). 
(3) On M 4 the metaconid is recognized as lower than the paraconid, 
but the protoconid (which is broken) is said to be certainly lower than the 
paraconid and apparently also lower than the metaconid. The hypoconid 
(corroded) is said to be decidedly, rather than slightly, lower than the 
hypoconulid and entoconid. 
After careful direct comparison it is clear that Matthew’s specimen 
must originally have been exactly like the present specimen in all these 
particulars, although its true nature in these details could not have been 
established until this less worn specimen was at hand. This is insisted 
upon only because, as previously suspected, it causes all discrepancy in 
molar structure between E. browni and E. cutleri to disappear, confirms 
their reference to the same genus, and, as other differences are quite un- 
important, necessitates their union as a single species: Eodelpkis cutleri. 
Like the type of E. cutleri, the present jaw is somewhat more robust 
than Matthew’s specimen (although the teeth are not larger), and the 
positions of the mental foramina, though similar, are not exactly the same 
in any two of the three specimens. These differences, however, are cer- 
tainly well within the range of individual variation. 
Relationships to Later Forms. Both Smith Woodward and Matthew 
recognized the similarity of this species to “Cimolestes” curtus Marsh 
from the Lance. The latter does not belong in Cimolestes and has been 
placed by the writer in a new genus, Diaphorodon^. Smith Woodward 
believed the trigonid to be more elevated in the earlier form. Matthew 
stated that “the lower molar figured by Marsh as Cimolestes curtus is 
somewhat similar to the posterior molars of Eodelpkis but the metaconid 
is more reduced, heel wider and shorter, its marginal cusps less differentiated, 
and the postero-internal cusps not so high or backwardly prominent. The 
tooth is considerably larger, agreeing more nearly with in size.” 
Although it can hardly be doubted that Eodelpkis and Diaphorodon are 
distinct genera, if only because of their wide geologic separation (no genus 
of dinosaurs is common to Lance and Belly River), the differences, in at 
least the posterior molars, are very slight. The difference in elevation 
of the trigonid is doubtful, and slight at best. The supposed differences 
in the heel are largely or wholly due to the corrosion, in different ways, 
lAm. Jour. Sei., (5) XIV, p. 127 (1927). 
93259— 3i 
