530 
ME. W. K. PAEKEE ON THE STEUCTUEE AND DEVELOPMENT 
I am also greatly indebted to Professor Huxley for his paper on Menobranchus (Proc. 
Zool. Soc. 1874, pp. 184-204, plates 29-31), and his article on the Amphibia in the last 
(ninth) edition of the ‘ Encyclopaedia Britannica.’ 
But those unspeakably important labours that dovetail into the front margin of my 
own work are now being carried on by a native worker of the highest ability : I refer 
to Francis M. Balfour, Esq., M.A.* * 
The reader is referred to the following memoirs, namely: — Friedrich and Gegenbaur, 
“ Her Schadel des Axolotl ( Siredon pisciformis ),” in the ‘ Berichte der koniglichen 
zootomischen Anstalt zu Wurzburg,’ 1849; Dr. Eobert Wiedersiieim on Salaman- 
drina [Seironota] perspicillata (Wurzburg, 1875), and his exquisite work, ‘ Das Kopf- 
skelet der Urodelen’ (Leipzig, 1877). 
In working out the skull of these forms, then, I have had much more light and help 
than in beginning the Batrachian skull, besides personal experience considerably enlarged, 
and new means of research that I have learned from younger labourers f. 
In the present paper my endeavour has been to bring into view all the morphological 
changes or metamorphoses undergone by a tailed Amphibian. But as the Axolotl 
[Siredon), in its occasional metamorphosis into a caducibranchiate Salamandrian, does 
not even in that give a full measure of the changes undergone by this group, I have 
added another type, namely Seironota. 
Moreover the larva of Seironota is very instructive, and fills up a lacuna left among 
my earlier stages of the Axolotl. 
Then, as the Perennibranchs are comparable to the larvse of the Caducibranchs, I have 
given here the structure of the skull in the lowest type of the former group, namely, 
that of Proteus anguinus — a type in which the form of the Fish is very thinly veiled, 
and whose relationship to both the Dipnoi and other generalized fishes is evident and 
unmistakable. 
It is in the Amphibia, both tailed and tailless, that the axial elements of the skull are 
combined with olfactory and auditory capsules that are beginning to show metamorphic 
modifications, which by plain and evident steps lead us onward and upward, as by a 
guiding hand, towards the almost untranslatable complexity seen in these organs in the 
higher types. 
chenden Anatomie der Wirbelthiere ’ (Leipzig, 1872). Professor Huxley’s work in this department, here 
especially referred to, is a paper on the skull of Ceratodus forsteri (Proc. Zool. Soc. 1876, pp. 24-59). 
* Besides Mr. Balfour’s part in Poster and Balfour’s ‘ Elements of Embryology ’ (London : Macmillan, 1874), 
I would refer the reader to his following invaluable memoir, ‘ A Preliminary Account of the Development of 
the Elasmobranch Pishes ’ (London : J. C. Adlard, 1874), reprinted from the ‘ Quarterly Journal of Microscopical 
Science,’ Oct. 1874. Further papers by Mr. Balfour on this subject will he found in ‘ The Journal of Anatomy j 
and Physiology,’ vol. x. pp. 517-570 and 672-688. Also by the same “ A Comparison of the Early 
Stages in the Development of Vertebrates,” in ‘ Studies from the Physiological Laboratory in the University 
of Cambridge,’ pp. 1-20 (Cambridge, 1876). 
f It is due to my son, Mr. T. J. Parker, to state that in modes of colouring objects, and in making fine 
sections, his help has been of great value to me. 
