86 SHUFELDT. (VoL. III. 
Huxley long ago drew up for us in the most lucid terms his 
excellent description of the salient characters to be found upon 
the basal aspect of the skull of an average passerine bird, leav- 
ing but little to be done here beyond instituting certain minor 
comparisons, and further on, pointing out exceptions to his gen- 
eral rule, which more recent investigations have brought to light.} 
Szalia is strictly passerine in the structure of these parts, espe- 
cially in the form of the vomer, as Professor Huxley describes 
that bone in the work just quoted. In a specimen of Szalza. 
mexicana, however, the maxillo-palatines are peculiar; their 
stems being markedly slender, while their mesial free ends are 
bulbous and hollow, with a full opening, in either one, to the 
outer side. 
In a specimen of Sza/ia arctica, a nestling, these bones have 
much the same form, though the free ends are not as bulbous 
at this age, and they come in contact, on either side, with the 
pointed free anterior end of the inner lamina of a palatine. As 
the form of the skull changes, due to advancing age, these ele- 
ments recede from each other, so that in adult specimens no 
such relation is ever discernible. A palatine is characterized in 
having its lamina very short in the antero-posterior direction ; the 
postero-external angles rounded; and the premaxillary process 
long and slender, being widely separated from the fellow of the 
opposite side. The rostrum of the sphenoid is rounded, thick, 
and stout; while each pzerygotd is comparatively long and slen- 
der ; and a guadrate wide in its transverse direction. Nothing 
need be said as to the manner of articulation among the bones I 
have mentioned, as in each case it is strictly passerine in Szalza, 
and we have been long fully informed upon such matters. 
We find nothing beyond what is already known to us in the 
internal aspect of the cranial casket of a Bluebird, nor in the 
sclerotals of its eyeballs, its ossicula auditus, the sesamoids 
posterior to the mandibular articulations, nor in its hyoidean 
apparatus. 
1 Huxey, THos. H., F.R.S., etc., “On the Classification of Birds; and on the 
Taxonomic Value of the modifications of certain of the Cranial Bones observable in 
that class.” P. Z. S., 1867, pp. 450, 451. And to enlist a foot-note of Prof. Huxley’s, 
as the works are not at my hand, the reader is also invited to refer to Nitzsch,“ Ueber 
die Familie der Passerinen,” in the Zezéschrift fiir die gesammten Naturwissenschaf- 
zen, 1862, and the article “ Passerinee ” in Ersch and Griiber’s Zzcyclopedie, 1840. 
