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Miolabis californicus Maxson, 1930, and a stenomyline camel
(previously unpublished record).
All California Institute of Technology collections are
now conserved in the Los Angeles County Museum of Natural
History. With the consent of this institution, the author
was able to study the entire sample of oreodonts from the
Tick Canyon fauna, which includes an additional maxillary
fragment collected by Miss Beth Chasse, an associate of the
museum.
Jahns (1940, p. 187) specified four specimens as
cotypes of the species Merychyus calaminthus; CIT 1383, 1382,
1342, and 1829. Although Jahns implies that all these
specimens are from a single quarry sample, CIT 201, the
labels on the specimens indicate that CIT 1342 was from
another locality within the Tick Canyon Formation, CIT 199.
Jahns considered the specimens CIT 1383, 1382, and 1842
adults and the other juvenile. An incomplete skull, CIT 1382,
entered significantly into his typification of~- calaminthus.
I believe this specimen represents a distinct species and
designate it the type of~- (Merychyus) jahnsi, described
below.
Schultz and Falkenbach (1947, p. 188) included a
discussion of the species M. (M.) calaminthus in their re-
vision of the subfamily Merychyinae, and redefined as a
single holotype LACM 1383. They concluded that the incomplete
skull, CIT 1382, represented a juvenile individual with di?4
and Ml-2, rather than an adult with Ml-3, as reported by
Jahns. I agree with Jahns in regarding LACM 1382 as a young
adult individual. This is based on several characters. The
most anterior cheek tooth present (Ml according to Jahns,
dp4 according to Schultz and Falkenbach) has well developed
roots and the character of the enamel is identical with that
of the more posterior cheek teeth. Deciduous dentitions
often bear smoother and lighter colored enamel, and this is
the case with the juvenile Tick Canyon specimens. Examination
of the order of replacement and occlusion in the genus
Merychyus, including the juvenile material in the Tick Canyon
sample, shows that the dP 4 and Ml are moderately worn before
the M2 begins to show wear facets. In LACM 1.382, the most
anterior tooth (Ml, this paper) is moderately worn, but the
next tooth (M 2 , this paper) displays very little wear. This
second tooth should be moderately worn if it is Ml as

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