In the anterior sections (at the level of the oculomotor foramen) the angulosplenial (angspl.) is a moderate-sized bone ([Fig. 15]). Meckel's cartilage (Mc. c.) is present as a small ovoid cartilage lying dorsolateral to the angulosplenial. Posteriorly, Meckel's cartilage is dorsal to the angulosplenial. The cartilage increases in size at the level of the posterior acoustic foramen, and the angulosplenial decreases in size posteriorly. At the level of the posterior border of the posterior acoustic foramen, the maxillary terminates and is replaced by the quadratojugal. The quadratojugal, ventral arm of the squamosal, pterygoid process, pterygoid, and Meckel's cartilage converge. At the level of the jugular foramen (jug. f.) ([Fig. 19]) the quadratojugal is incorporated into the squamosal-pterygoid process-pterygoid complex. The complex is narrowly separated by connective tissue from Meckel's cartilage ventrally. The quadrate process (quad. proc.) is represented by the cartilage bordered dorsally by the pterygoid process and the ventral arm of the squamosal, and ventrally by Meckel's cartilage. At the posterior terminus of the skull all bony elements of the articular region terminate, except for a small terminal part of the angulosplenial underlying Meckel's cartilage.
SUMMARY
Since no accounts comparable to the preceding for Smilisca baudini are available for other hylid frogs, it is meaningless to attempt any discussion dealing with character significance or variation within the Hylidae. There is considerable literature treating bufonids, leptodactylids, ranids, and various Old World genera (see Baldauf, 1955, for a review of these works). Likewise, a comparison at the familial level based on the study of a single species seems inadequate and premature. By way of summary and synoptic description a list of cranial osteological characters of Smilisca baudini is presented. The items selected enable comparison with similar compilations by other workers, and are based in part on my unpublished observations of other hylids.
1. Compared to hylids not having integumentary-cranial co-ossification, the dermal roofing bones of Smilisca baudini are extensive, and the skull is well-ossified internally. In contrast to most casque-headed hylids (those having integumentary-cranial co-ossification), the dermal roofing bones are much less extensive, the dermal sphenethmoid (see Trueb, 1966, p. 563) is absent, and internal ossification is less extensive.
2. The solum nasi is not ossified; the septum nasi is ossified only posteriorly, and the olfactory eminence is supported by the cartilaginous solum nasi and the bony prevomer.
3. The lingual process is absent. There is no palatal cartilage isolated between the premaxillaries.
4. The anterior end of the cavum medium lies anterior to the cavum inferius.
5. The septomaxillary is basically a U-shaped structure and has a dorsal, anteriorly curved, ramus on the lateral branch and a longitudinal loop of bone ventrally.
6. A distinct pars nasalis is absent on the maxillary.