290 MR. W. K. PARKER ON THE STRUCTURE AND 
Since the older writer, no native anatomist has arisen more fitted to hold and to 
handle this difficult subject than the author of those ** Lectures.” 
I shall follow up this matter from point to point in the same manner as that pursued 
in the papers already offered to the Society; and my endeavour is to link on paper to 
paper so that they may form an organic whole, the idea and purpose being the same in 
each, and the special mode of treatment the same. 
In the present communication more re/ative anatomy has been given than in the 
former papers; I have to steer between the confusion arising from the display of too 
many parts, and the baldness of a mere account of skeletal structures. 
If the nasal and auditory sense-capsules were as easy of elimination as the eyeball, the 
skull and face would present a much less complex problem; but they soon become part 
and parcel of a most intricate cranio-facial unity, and everywhere intrude themselves 
upon the observer. 
A certain convenient subdivision of this especial piece of morphological work can be 
made; thus we have— 
Ist. The notochordal region of the skull. 
2nd. The pronotochordal region of the same. 
srd. The facial arches. 
Ath. The sense-capsules. 
The metamorphosis of the original and, as it were, /arval parts here obtains its highest 
degree; the distance which has to be travelled by the morphologist between the starting- 
point and the goal may be conceived of if the primary form (Plate XXVIII. fig. 5) be 
compared with the finished condition of the skull (Plate XXXVI. fig. 4). 
In observing the growth-changes that bring about this result, a large amount of 
histological labour is involved; in the present piece of work that part of the research 
has been taken pains with as much as if it had been intended to write upon the 
tissues, and not upon their massing and arrangement. The determination of homo- 
logous parts in this type, as compared with the elements that build up the skull of the 
Fish, the Frog, and the Bird, has not been by any means the most difficult part of 
my toil; they arrange themselves, and assume their own titles, in a very ready manner ; 
for the difficulties of terminology will all melt away as soon as a sufficient number 
of types have been traced down to their embryonic “ roots.” Many parts will have to 
be re-named; but this will be easy work when the true reason for the change is made 
plain. 
As the skeletal parts are all composed of the various kinds of ‘* connective tissue,” 
and as these kinds are intimately related to, and often pass insensibly into, one another, 
it is not easy to keep to a consistent terminology in describing them. 
This class of tissues becomes hardened by bone-salts at very different ages; and in any 
homologous territory, if ossification is /ate, the tissue becomes hyaline cartilage first; in 
other types the like tract may become beny, whilst, as yet, the tissue is extremely soft 
and young: in intermediate conditions bone is formed in a tissue which is indifferent ; it 
