652 
MR. W. K. PARKER ON THE STRUCTURE AND 
and less massive than in the Batrachia generally, being intermediate between that of 
an ordinary Tadpole (or even that of Dactylethra) and the hyoid of an adult Sala- 
mandra maculosa. It is also peculiar in uniting with its fellow, and showing no 
separate basal piece (compare Plate 56. fig. 6 with Plate 60. fig. 4, c.liy.). 
The remaining four arches are the “ branchials ” ( hr . 1-4) : these, where they touch 
above and below, are coalesced ; they have no basal piece chondrified, although between 
them they have not only the rudimentary larynx (lx.), but also a large triangular patch 
of dense granular tissue, which chondrifies afterwards. These bars are flat, thin, some- 
what pointed above, and below meet in one common isthmus uniting the right and left 
bars. These bars are supplied with the usual branchial arteries ; but I can discover 
neither secondary branches to these, nor branchial filaments to which such branches 
should be distributed. 
Notwithstanding the feeble condition of these bars, this is their highest state of 
development (compare Plate 58. fig. 1 with Plate 60. fig. 4, hr. 1-5) ; they, indeed, remain 
in a fused and altered state ; but the hyoid is at its height now, and will have vanished 
in the ripe young (Plate 60. fig. 7). 
There is no such superfluity of cartilage growing from the auditory capsules as in 
Dactylethra ; but the tegmen is a very distinct eave to the huge ovoidal capsules ; they 
are fully chondrified, even above, and so quite come up in this respect to the first stage 
of Dactylethra (Plate 56. fig. 4). Beneath, the fenestra ovalis and its enclosing fossa is 
more advanced than in that larva. It nearly corresponds with that of the Common 
Toad’s Tadpole when it is two thirds of an inch long, a little shorter than these embryos 
of Pipa (Plate 55. fig. 5), but which has been for two or three weeks an active self- 
determined larva. 
In this stage the future fenestra ovalis (fig. 3 ,fs.o.) is a somewhat triangular depres- 
sion, with the longest angle, like a lacerated wound, running backwards and a little 
inwards ; in this, its faintest part, the perforation will take place. The obtuse, middle 
angle of this fossa looks inwards, and the foremost, which is rounded, forwards and out- 
wards. Above the crescentic open space between the front of the capsule and the 
mandibular pier the 2nd and 3rd branches of the trigeminal nerves pass towards their 
destination ; below that space the thyroid gland (1) ( tr.g .) lies ; behind the capsule the 
9th and 10th nerves are seen emerging:. 
No further light upon the morphology of this peculiar chondrocranium was obtained 
by upper views, and only a partial figure of that aspect is here given (Plate 61. fig. 1), to 
show the size and relations of the “ orbitar process.” At present the side walls of the skull 
are not chondrified, and the conjoined trabeculae form merely a flat internasal plate*. 
* Notwithstanding the anxious care required to work out such chondrocrania as this and that of the younger 
Dactylethra , I consider that their elucidation has amply repaid me ; they light up each other, satisfying the 
self-suspecting observer, when he sees the most strange modifications reappear a little altered. Conforming in 
all essentials to typical, larval, skulls of Batrachia, their most striking aberrations will he found to have 
meanings that relate to types beyond their own group, meanings also that will not all meet the eye until 
more is seen and known. 
