DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
stout angular styloid process, on the upper surface of which there is a large, oval, 
convex condyle, which rolls in the shallow cup of the suspensorium. 
The sinuosities of the hyoid bar are filled in by the convexities of the branchial 
apparatus. In the middle, behind the soft basi-hyal, there is a large pyriform basi- 
branchial (Plate 10, fig. 6, b.br), composed of hyaline cartilage ; a short process on the 
postero-inferior surface of this is the rudiment of a second basi-branchial segment. 
Outside and behind this median piece there is a pair of flat lozenge-shaped cartilages, 
the hypo-branchials (Ji.br.) ; these grow outwards and are connected with cartilages 
above (inside) and below (outside) ; these latter are the branchial pouches. 
Two of the small upper cartilages are distinct from the hypo-branchials, but are 
partly confluent with the large outer bars (c.br 1 ., c.br 3 ., ex.br.) ; the two hinder rudi¬ 
ments (c.6r 3, 4 .) are continuous with the hypo-branchial plate, and the space between 
the two is filled in with cartilage. 
The first and fourth outer bars ( ex.br h, ex.bi A . ) are pouch-like, the others are thin 
broad bands. 
The rudimentary inner arches {c.br.) are less differentiated than in the larva of 
the species of Rana and of other kinds ( Cyclorhamphus, Calyptocephalus, Cystignathus, 
&c.) that I have worked out. 
These parts are at their fullest development at this stage. 
I have already mentioned the roof-bones in relation to the fontanelle; the para- 
sphenoid is a dagger with a guard, but without a handle. 
It seems small, yet it occupies the same place, and has precisely the same relations 
as in the adult (Plate 2, fig. 2; and Plate 10, fig. 2, pa.s.); it is one-thircl longer 
than in the old male. Even now it is split in front : a character which is retained 
throughout life. 
17 (continued).—(B) Second Tadpole of Pseudis paradoxa. —7 inches long; tail, 
4§ inches ; greatest width of tail, 2 inches ; hind legs, 3 inches long; fore legs 
hidden. 
In this stage the legs are six times as long as in the last, and the tail two-thirds the 
length and half the width; here the chondrocranium is but little more than half as broad 
across the suspensoria and only two-thirds the length.* 
There are many things to be noticed in this stage besides its lessened size and more 
oblong general shape. 
And first, the Selachian character of a huge notochord enclosed in a tubular azygous 
cartilage is now as difficult to find as in most Tadpoles; it has become part of the basal 
plate by coalescence with the “ parachordals” and trabeculae, and the gelatinous axis is 
* If I had only found these discrepancies in size in two or three, I should have thought it accidental; 
but my specimens are too numerous, and run over too many stages, for there to be any mistake: the skull 
in the third stage (C) is but little more than one-third the length of that of the youngest (A). 
MDCCCLXXXI, L 
