660 
MR. W. Iv. PARKER ON THE STRUCTURE AND 
All that remains of the hyoid arch (Plate 60. fig. 7) now is the fore end of the basi- 
hyobranchial bar (see in Dactylethra, Plate 58. figs. 4 & 5, b.hy., b.br.). This part did not 
exist in the first stage (Plate 60. fig. 4) ; but the median bar has appeared with the 
disappearance of the “ cornua,” and already the metamorphosed branchials are the very 
true counterparts of what we see in the adult Dactylethra (Plate 58. fig. 5), save that 
the hyoid bands are gone. 
Here the second basibranchial [b.br. 2) has now become cartilage (Plate 60. fig. 7, 
b.br. 2), and is, relatively, much larger than in Dactylethra (Plate 58. fig. 5, b.br. 2). In 
that species, as in Pipa , the first basibranchial is fenestrate, and the first and second 
branchials (br. 1 , 2) are molten together and spread out into a large flat plate, pyriform 
here, oblong in Dactylethra. Here the third and fourth {hr. 3, 4) branchials (their lower 
or hypobranchial ends) have formed the thyro-hyals, but they are not yet ossified as in 
the old Dactylethra. In Dana temyoraria (“ Frog’s Skull,” plate x. figs. 1 & 2, th.) there 
is no second basibranchial to underlie the larynx (lx.) ; and, seeing the relation of the 
second basibranchial of the Newt to its larynx, Professor Huxley has been led to doubt 
the correctness of my description (op. cit. p. 185) of these parts. Pipa and Dactylethra 
answer forme, for they possess both the median thyro-hyal of the Urodele and the paired 
thyro-hyals of the Anuran. 
The remainder of this demonstration is by far the easier part, for the skull in the 
little ripe embryos had undergone the most striking and important changes. Its meta- 
morphosis was fairly perfect, relative change of size or degree of hardening being nearly 
all that remained over to the growing Pipa. 
Skull of Pipa monstrosa. — Third Stage ; the adult Toad. 
There can scarcely be a more remarkable skull than this ; the sense of hearing would 
appear to be of more consequence to this Toad than that of sight, for the eyes are but 
little grown (Plate 62. fig. 1, e ), whilst the organs of hearing are thrown out on long arms 
much as the eyeballs are thrown out in the Hammer-headed Shark. Therefore many 
things in the skull are contrary to what we find even in the nearest of kin, namely, the 
other tongueless kind (Dactylethra, Plate 59). The general appearance of the skull 
suggests the idea of a log-house hastily thrown together, and not a fitly framed structure 
compacted together with the utmost architectural care and skill. A little of the old 
cementing cartilage there is, and strong bands and sheets of fibrous tissue in places ; but 
in the main it is made up of slabs, and planks, and bars, placed lengthwise, slanting, and 
across. These, moreover, look as though they were fresh from the tools of the hasty 
framer. 
Behind (Plate 62. fig. 1-4, oc.c.) the occipital condyles have their faces turned the 
contrary way ; they look outwards, and are unusually flat. The dense, stout occipital ring 
is all bony, save below (fig. 2, b.o.) ; for, true to its Batrachian character, it has a soft 
basioccipital. The great, outstanding occipito-otic “ arms ” are one single mass of 
bone, although on the under face there is a second transverse slab in front of the other 
