cus_, L.,
ancient. _Delorhynchus_ is masculine because of the ending that it
acquires when transliterated into Latin.)

_Type specimen._--Fragmentary left maxilla, bearing four teeth, KU
11117.

_Referred specimens._--Fragmentary right maxilla having four teeth, KU
11118; fragmentary left maxilla having four teeth, the most posterior of
which has been broken, KU 11119.

_Horizon and locality._--A fissure deposit in the Arbuckle limestone at
the Dolese Brothers Limestone Quarry, approximately six miles north of
Fort Sill, in sec. 31, T. 4 N, R. 11 W, Comanche County, Oklahoma. These
sediments are of early Permian age, possibly equivalent to the Arroyo
formation, Lower Clear Fork Group of Texas (Vaughn, 1958: 981).

_Diagnosis._--Small; marginal teeth conical, slender and recurved at
tips; marginal tooth-row without caniniform enlargement; narial opening
enlarged and bordered dorsally, posteriorly and ventrally by maxilla;
maxilla with foramen opening laterally at posteroventral corner of
naris.

_Description_ (based on 3 maxillary fragments, see Table 1).--Each of
the maxillary fragments bears four thecodont teeth. These are conical,
slender and sharply pointed; in their distal third they are slightly
recurved, laterally compressed, and have anterior and posterior
non-serrated cutting edges. In medial aspect at their bases, the teeth
are longitudinally striated. The bases of the teeth are circular in
cross-section and are slightly bulbous. There is no caniniform
enlargement of any of the teeth, the longest tooth of each fragment
being differently placed in the series of teeth and little longer than
the others. There is no swelling on either the internal or external
surfaces of the maxillae. The teeth are in a continuous series; no
diastema or maxillary step is evident.

[Illustration: FIGURES 1-3. _Delorhynchus priscus_, lower Permian, 6
miles north of Fort Sill, Comanche County, Oklahoma. All x 3.

FIG. 1. KU 11117 (type specimen), lateral view of left maxilla.
FIG. 2. KU 11118, lateral view of right maxilla.
FIG. 3. KU 11119, lateral view of left maxilla.]

The fragments have been broken along similar lines of fracture, and each
is approximately rhomboidal in shape. The maxilla encircles the
posterior border of the naris and extends dorsally above the naris to an
extent sufficient to indicate the probable exclusion of the lacrimal
bone from the narial border. At the posteroventral corner of the naris a
foram