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and describes a left pes. This specimen was not definitely
associated with any of the skull remains, so it cannot be
unquestionably referred to either species.

Merychyus (Merychyus) jahnsi sp. n. Figure 1

~: Part of a skull with M 1 - 3 ; figured as a cotype of M.
(Merychyus) calaminthus by Jahns, 1940, plate 2, figure 2-
and 3a; LACM 1382. The LM 1 was absent in the original
figure but was found in the collection and replaced on the
specimen.
Referred material: Nearly complete skull and mandibles of
a juvenile, LACM 1829; incomplete skull and mandible of
young juvenile, LACM 1384, and juvenile maxillary fragment
with C erupting and with dpl-L~, LACM 13431..
Locality: Same as for _!i. (Merychyus) calaminthus.
Etymology: Named in honor of Professor Richard H. Jahns,
in recognition of his original work on the Tick Canyon fauna.
Diagnosis: Smallest recognized species of the genus
Merychyus, a number of measurements averaging 15 per cent
smaller than _!i. (Merychyus) crabilli (Fig. 2); low flat
skull, supraoccipital wings widely spread; shallow antorbital
fossa, small prelacrimal vacuity with triangular outline;
lightly constructed malar; paired infraorbital foramina
above p3, superior molars subhypsodont.
Description: Skull: By combining the type and the referred
fragment of cranium, LACM 1829, a description of nearly the
entire skull is possible.
Jahns (1940, p. 187): 'I'he dorsal surface of the
skull, as seen in CIT 1382, is low and flattened,
with its highest point at the postorbital constric-
tion. The brain case has a nearly circular horizontal
cross section, and its upper surface is marked by
two broad, very low temporal ridges. These ridges
pnite just in back of the glenoid fossae to form a
short, narrow·sagittal crest that is clearly
defined but not prominent. The occipital crests are
sharp and well developed.
(po 188) The malar is of medium build, but the
zygomatic arches are light. The elevated orbits
are rather small and only slightly elongated

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