OF THE SKULL IN THE UKODELOUS AMPHIBIA. 
589 
tongue-shaped prenasal in the adult ; and these also show a free prorhinal, or lobe of the 
cornu trabeculae, on each side. 
These paired processes are very constant in the Batrachia, but in them the prenasal 
is generally a mere bud. 
In the Batrachia the nasal capsules, with the conjoined trabecular (subnasal) laminae, 
are more developed than in the other group ; they also have a larger “ appendix alae 
nasi,” formed of the outer three fourths of the upper labial. 
The suspensorium develops a quadrate lone in Urodeles, save in Siren. This is absent 
in Batrachia generally, but present in Dactyletlira and Bufo agua. 
The “ pedicle ” is single in Proteus, double in the rest of the group. In that type, 
in Menolranchus , Siren, and Menopoma, it grows up to the trabecula, as in the 
Batrachia. 
In most Urodeles, however, the lower fork, or jpedicle proper, is attached to a plaster 
of investing cartilage on the face of the ear-capsules by a mass of fibrous tissue. 
In the Frog ( Bana temporaria) the attached part of the simple pedicle is absorbed, 
and the lower, swollen part forms a condyle, and there is a joint-cavity, instead of a fibrous 
bed, where it hinges on the capsule. 
In the Toad ( Bufo vulgaris ) the apex of the pedicle merely coalesces with the front 
of the capsule, and is not absorbed. 
In the Urodeles, with the doubtful exception of Proteus *, there is a dentigerous 
splenial, besides the dentary and articulare. In the Batrachia there are only the two 
latter hones. 
In the Urodeles the little mento-Meckelian bone, which characterizes the Frog’s 
mandible, only imperfectly appears in Proteus. 
The epivisceral element of the second arch occurs as a large hyo-mandibular in 
Proteus, and as a smaller segment in Siren and Menopoma ; but as a rule it is sup- 
pressed, and the stapes is merely connected to the suspensorium by a ligament, the 
“ suspensorio-stapedial.” 
The cerato-visceral is large, hut it does not ascend to the ear-capsule. It is connected 
to the suspensorium by the hyo-suspensorial, and to the angle of the mandible by the 
mandibulo-hyoid ligament. 
Distally it sometimes gives off its hypohyal piece to coalesce with the first basi- 
branchial at its fore end. In some kinds this distal piece becomes very slender and 
retrally directed. In the Menopome it is subdivided into three pieces; in Osseous 
Fishes it has two bony centres. 
In the Frog the hyoid arch becomes very slender, coalesces with the basihyal, and, 
above, ascends to attach itself to the auditory sac. This, however, is only the cerato- 
hyal element ; it has no hypohyal piece ; and this is a common thing, namely, for two 
hypovisceral elements in one type to be represented by a basivisceral in another. 
In Bufo vulgaris the top of this piece (the stylohyal region) coalesces with the ear- 
* Wiedeesheim figures it in his new work on the Urodeles (plate 2. fig. 16). 
