DEVELOPMENT OE THE SKULL IN THE EATEACHIA. 
60 : 
As in tlie adult Urodelous Amphibian, so in the larval Amiran, certain parts are 
abortively developed or even quite suppressed. 
In the metamorphosed young of the Common Frog and Toad these parts appears 
but not until after the lapse of some time ; this anachronism is much less in Pipa and 
Pseudis*. 
The advantage of working independently, and yet with constant intercommunication 
both by word and letter, with no little controversy and mutual criticism, seems to me 
to be very great ; this has been of late more than ever the plan adopted by Professor 
Huxley and myself. 
Many unresolved doubts still await further labour ; and in some points of nomen- 
clature I hold to what I gave in my former paper. In the account here to be given of 
the skull of Pactylethra and Pip a I shall give more time and care to even the adult 
skull than the author of the article “Amphibia” (just referred to); and, besides this, 
I have succeeded in obtaining early stages : thus I possess a sure key to the difficulties 
of the adult skull f . 
On the Skull of the adult Common Frog (Kana temporaria). — Nasal region. 
Before my former paper was in print, I had seen and figured the free trabecular cornua 
projecting from the nasal capsule of the adult Bull-frog ( Pana pipiens) ; but I had 
missed them in the common kind, and supposed that they were peculiar to the larger 
type. But, in his article “ Amphibia,” Professor Huxley figured and described them in 
Pana esculenta (p. 755, fig. 9, r.p.) as “rhinal processes.” These are not shown in my 
figures of the chondrocranium of the adult P. temporaria (“ Frog’s Skull,” Phil. Trans. 
1871, plate'ix. figs. 6 & 7). I doubted their existence in that type ; but early in 1874 Prof. 
Huxley sent me a pen-and-ink sketch of them in this species, and I soon after found them 
myself (Plate 54. figs. 1, 2, c.tr.). The same letter gave the position of one of the two per- 
manent upper labials (u.l.') ; the other ( u.l .") was soon found by me, and then it was seen 
that much of the nasal outworks are formed, in the adult skull, of the greater segment of 
the originally simple upper labial (“Frog’s Skull,” plate v. figs. 3 & 4, u.l.). These, in 
the specimen figured in the present paper, were quite distinct from the true alinasal and 
aliseptal folds of cartilage ; they may, however, become coalesced in the adult, as they 
certainly do in the Toad (Plate 54. figs. 3-5) J. 
* At present I can only compare the skulls of the Anura and Uroclela, not having worked out the Peromela 
(Csecilians) ; for an account of this type of skull the reader is referred to Prof. Huxley’s description of the skull 
of the adult Epicrium glutinosum (Enc. Brit. art. Amphibia, p. 761). 
t I have to thank Professor Huxley for the loan of adult skulls of Pip a and Pactylethra ; Dr. Dobson, E.L.S., 
of Netley, for another adult Pactylethra ; my friend, Mr. T. J. Moore, of Liverpool, for nine larvas of various 
stages of Pactylethra (besides most valuable specimens of other kinds); Professor W. H. Elower, E.B.S., for 
permission to examine specimens of ripe young of Pipa contained in the Museum of the Royal College of 
Surgeons ; and Dr. Gunther, E.R.S., for tadpoles of that type. 
t The relation of the upper labials to the vestibule of the nasal labyrinth is of great interest ; I have carefully 
worked out these parts in Sharks, Skates, Teleostei, Anura, Serpents, many kinds of Birds (Trans. Linn. Soc. 
ser. 2, vol. i. plates 1-5 and 20-27 ; and Trans. Zool. Soc. 1875, vol. ix. plates 54-62), and in the Mammal (the 
“ Pig’s Skull,” Phil. Trans. 1874, plates xxxi.-xxxvi.). 
4p 2 
