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XXIV. On the Structure ancl Development of the Shull in the Batrachia. — Part II. 
By William Kitchen Parker, F.B.S. 
Beceived October 28, — Bead December 16, 1875. 
Introductory Bemarfcs. 
The first paper offered by me to the Royal Society on the structure of the skull in this 
group was on that of the Common Frog ; this has been followed by a similar piece of 
work treating of the Salmon’s skull, and this latter by another on that of the Pig. 
But these are merely an earnest of what I have in hand, and hope in due time to 
offer to the Society — my one steadfast desire being to master the problem of the skull, 
and to have the results of my labours published in the ‘ Philosophical Transactions.’ 
My former memoir on the Batrachian skull was wrought out under very great diffi- 
culties ; I was not guideless absolutely, and yet much of my way had to be felt out 
in the dark. After exactly four years had elapsed from the reading of that paper, 
Professor Huxley, my main helper before, took up the Amphibian skull once more 
(his earlier researches were partly given in his £ Croonian Lecture ’ delivered in November 
1858); and this new work* resulted in the discovery of sundry errors and deficiencies 
in my account of the development of the Frog’s skull. These criticisms given to me 
orally soon commended themselves to my own mind, now gaining greater light ; and 
the great difficulty of the subject, a difficulty acknowledged freely by my friend and 
guide, has acted in producing the intensest desire in me for a fuller knowledge of these 
most instructive, if perplexing, types. 
It was unfortunate for me that I took up by far the more difficult problem, namely, 
that of the skull of the 6 Anura,’ whereas that of the ‘ Urodela,’ the Salamander and its 
companions, is a much simpler structure, undergoing much less metamorphosis. 
Therefore the masterly account given by Professor Huxley of the skull of Meno- 
hranchus, a very low and simple type, has shed a most welcome light upon the skull of 
these air-breathing ‘ Ichthyopsida.’ 
We have now carefully worked, more or less in each other’s view, at the structure 
and development of several types of skulls of the Anura and Urodela ; and at last the 
truth of the matter seems to be revealing itself. 
In the present paper I shall show, as I proceed, all those deficiencies and actual errors 
which now, after these years, and after fresh and much holpen labour, appear in the 
older memoir. 
* See the article on Amphibia in the new edition of the ‘ Encyclopaedia Britannica,’ and his paper on Meno - 
branchus in the ‘Proceedings of the Zoological Society,’ March 17, 1874, pp. 186-204, plate3 29-32. 
MDCCCLXXVI. 4 P 
