id processes to the effect on swallowing
prey. Evidently many of the coelacanths, _Latimeria_ for example, are
predators (Smith, 1939:104); to such fishes a more efficient catching
and swallowing mechanism would be an adaptive improvement. Stensioe
(1932:fig. 14) presents a cross section of the ethmosphenoid moiety of
the endocranium of _Diplocercides kayseri_ (von Koenen) showing the
metapterygoid of the palatoquadrate loosely articulated to both the
antotic and basipterygoid processes. According to Tchernavin (1948:137)
and Schaeffer and Rosen (1961:190) the swallowing of large prey depends
on the ability of the fish to expand its oral cavity by allowing the
posteroventral portion of the palatoquadrate and the posterior end of
the mandible to swing outward. Where the palatoquadrate articulates with
the basisphenoid at the antotic and basipterygoid processes, as in the
Devonian coelacanths, it can not swing so far laterally as where it
articulates with only the dorsal, antotic process. Perhaps the loss of
the basipterygoid articulation reflects the development of a more
efficient mechanism for swallowing prey in these fishes. Schaeffer and
Rosen (1961:191, 193) show that in the evolution of the actinopterygians
several changes improved the feeding mechanism: some of these changes
are: (1) freeing of the maxilla from the cheek, giving a larger chamber
for the action of the adductor mandibulae; (2) development of a coronoid
process on the mandible; and (3) increase in torque around the jaw
articulation. In coelacanths, at least some comparable changes occurred,
such as: (1) loss of the maxillary, thus increasing the size of the
adductor chamber; (2) development of the coronoid bone, affording a
greater area for muscle attachment; (3) development of an arched dorsal
margin on the angular; (4) modification of the palatoquadrate complex,
with resultant loss of the basipterygoid processes. In _Synaptotylus_
the basipterygoid processes are small, not basally located, and perhaps
not functional. A more efficient feeding mechanism developed rapidly
during the Carboniferous and has remained almost unaltered.

[Illustration: FIG. 2. _Synaptotylus newelli_ (Hibbard). Restoration of
the parasphenoid, based on K. U. nos. 9939, 11451, x 5. A, ventral view,
B, dorsal view and cross sections.]

The parasphenoid (see fig. 2) is a shovel-shaped bone having a wide
anterior portion and a narrower posterior portion of nearly uniform
width.