achycephalidae [= Atelopodidae; Dendrobatidae;
and Leptodactylidae (in part)] by Noble (1931). _Allophryne_ possesses
well-developed, free epicoracoidal horns, such as those found in the
Hylidae, Centrolenidae, Leptodactylidae and Bufonidae.

The presence of intercalary elements in the digits is characteristic of
the Centrolenidae, Hylidae, Phrynomeridae, Pseudidae, and the
rhacophorine ranids (including the Hyperoliidae). This element is bony
in the pseudids and cartilaginous in the other families. Phrynomerids
and rhacophorine ranids lack epicoracoidal horns and have firmisternal
pectoral girdles. Centrolenids are small, delicate, arboreal frogs
having poorly ossified skulls and fused tarsal bones, but agree with
_Allophryne_ in having T-shaped terminal phalanges.

[Illustration: FIG. 2. Dorsal (_a_) and lateral (_b_) views of
distal phalanges of third finger of _Allophryne_. x 40.]

Only the presence of intercalary cartilages (Fig. 2) suggests
relationship of _Allophryne_ to the Hylidae. The T-shaped terminal
phalanges suggest affinities with centrolenids, elutherodactyline
leptodactylids, or certain "brachycephalid" frogs. Griffiths (1959)
clearly showed that Noble's Brachycephalidae was a polyphyletic
assemblage. No hylid genus is edentate, and none has either T-shaped
terminal phalanges or the unusual dorsal spinules. Perhaps the presence
of intercalary cartilages is not indicative of relationship but instead
is a parallelism (or convergence) in _Allophryne_ and genera of the
Centrolenidae.

CRANIAL OSTEOLOGY

The skull of _Allophryne_ (Fig. 3) is distinctive among
anurans; it does not closely resemble the skulls of either
hylids or centrolenids, both of which have generally more
delicate (except for casque-headed hylids, such as
_Corythomantis_, _Diaglena_, _Osteocephalus_, _Triprion_)
and generalized skulls. _Allophryne_ on the other hand has a
strongly ossified central region (cranial roofing bones and
sphenethmoid complex) and a weak peripheral zone. The
peripheral elements are reduced (maxilla, pterygoid, and
squamosal) or absent (quadratojugal), whereas the
frontoparietals, nasals, sphenethmoid, prooetics, and
exoccipitals form a compact central zone. An elongate
frontoparietal fontanelle is present.

[Illustration: FIG. 3. Dorsal view of skull of _Allophryne_
(AMNH 70110). x 12.]

Dorsally (Fig. 3), the premaxillae are not vis