DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
69 
1. The septo-maxillaries are suppressed (?). 
2. The fronto-parietals confluent behind. 
3. The pro-rhinals doubled over as hooks. 
4. A distinct sharp prenasal. 
5. Very narrow nasal roofs. 
6. No inter-stapedial segment. 
7. No supra-stapedial band. 
8. A large long uncinate “ extra-hyal.” 
The folding over of the pro-rhinals, the length of the prenasal, the generalised state 
of the columella, and the additional hyoidean element, indicate a very marginal posi¬ 
tion for this type in the Family “Ranidae.” 
Second Family. “ Cystignathida:.” 
First genus. Pseudis. 
17. (A) Skull of Pseudis paradoxa. —First larva ; total length, 10g inches ; head and 
body, 3g inches; tail, 7 inches; greatest width of tail, 4 inches; depth of body, 
2|- inches ; hind legs, \ inch. S. America. 
A side view of this, the youngest and largest Tadpole of Pseudis (natural size) (Plate 1, 
fig. 1), shows to what a magnitude the larva of a medium-sized Frog may grow ; for 
the old individuals are but little larger than our native Grey Frog. 
As to actual length, more than two-thirds of this larva is a temporary structure, 
and belongs to the tail; the bulbous fore part, below, is half pharyngeal and half 
abdominal. 
Supposing a measurement by vertical lines across the length of the creature, the dis¬ 
tance between the anal aperture and the occipital hinge is one-third the length of the 
essential animal; the single gill-opening (left side) is at the middle; and the eye-ball 
two-fifths from the front. 
Altogether, the outlets and inlets to the essential animal are Jive: three azygous—the 
oral, anal, and pharyngeal; and two paired, the narial; these latter are above and behind 
the upper lip, and are small and rounded: they open into the palate almost vertically. The 
mouth is small but complicated (Plate 1, fig. 2), the upper labials (Plate 2, figs. 1, 2, u.l .) 
arching over the horseshoe-shaped lower labials (Plate 10, fig. 5, l.l .) and the small oral 
passage opening being between the halves of the horseshoe : the skin over these labials 
is formed into a horny plate, and the plicce of the lips are developed into horny rasps. 
Much fibrous tissue—some watery, some strong and tough—encloses the skull and 
the outworks ; above, the head is marked by a median, and a pair of lateral, ridges ; 
the facial cartilages are spread out on each side and lie on a plane but little below that 
of the cranial cavity (see Plate 2). 
The “ chondrocranium ” at this stage is one of the best for comparison with that of 
