670 GEOLOGICAL SURVEY OF THE TERRITORIES. 
perchance the thickness, of the internal and external sclerotic coats 
that cover them. Lately we saw in the case of Sayornis nigricans where 
these platelets were apparently confluent ; no such condition ever occurs 
in the Grouse or Partridges. 
The “lacrymal” (Plate V, Fig. 51, 3 and other figured skulls), is 
found on the anterior margin of the frontal, enjoying a free harmonial 
articulation that encroaches slightly on the nasal border. Each is a 
squamous, cordate lamella, with its larger end nearer the orbital eavity ; 
this completes the bone in young birds, but in mature individuals it 
sends down acurved and delicate style with its point directed outwards, 
that encircles and gives support to the lacrymal duct on its passage to 
the rhinal cavity (Centrocercus). 
We now come to examine into the last of the cranial vertebra, and, 
in the family under consideration, the one most modified. It is the 
“nasal,” and its neural arch the “ rhinencephalic,” the hemal, the 
“maxillary.” 
In the Yetraonide its centrum, the ‘ vomer,” is missing. Whether 
this be due to the foreshortened skull of the Grouse, with its long sphe- 
noidal rostrum rendering any further extension superfluous, we cannot 
say. In the lengthened skull of any of the Anatide, where such a bone 
is imperatively called for, as a sub-interspinal partition, it is invariably 
present and unusually prominent (Plate V, Fig. 51, vr. vomer, is merely 
outlined to indicate its position in other birds). 
The neurapophyses of the arch are found in the connate prefrontals, 
the bone called “ethmoid” in androtomy. It here, in the young bird, 
is lodged in the outer third of the groove on the pre-sphenoid, rises 
columnar, sub-compressed laterally, leaning forwards at a gentle angle 
to expand above in a trihedral summit for the support of the frontals, 
nasals, and intermaxillary, a short process being projected backwards 
for the former. The posterior aspect of the column develops as the bird 
grows, the interorbital septum, reaching to, and perhaps aiding in, the 
formation of the exogenous orbito-sphenoids. 
The nasals, or the divided neural spine of the arch, are squamous 
1Since making the above statement Ihave been able to examine a large mass of 
material from all imaginable sources, and have come to the final conclusion that the 
vomer occurs in the entire group of gallinaceous birds of America. Many things may 
have led me to believe at the time that this bone was missing, as stated in the text: 
In the first place, it is an extremely delicate and freely articulated onein the Tetraon- 
ide, and in the second place the doubt still harasses my mind as to whether there 
may not be instances where this vomer does not ossify until very late in the life of the 
bird, and all of the fresh specimens I examined may have been of this character. The 
foundation for this assertion lies in the fact, that quite recently I examined, with 
great care, numbers of market specimens of Bonasa and Cupidonia, in which I failed 
to discover this bonelet, while in others it was easily found. The specimens exam- 
ined were all apparently birds that had attained maturity, and displayed no external 
characters by which they could be separated from each other. 
The plates accompanying this edition were not submitted to me in time to add this 
bone to such figures in which it would show, so that the vomer does not appear in 
any of them. In Plate V, fig. 51, where it is shown in dotted outline as vr., it should 
be beyond the ethmoid, Pf. and shaded like the other bones indicating its presence. 
A good figure, giving its proper position, is presented to us by Huxley in his Anatomy 
of the Vertebrated Animals, page 283 (figure 82 of the common fowl). This writer 
tells us ‘‘the vomers vary more than almost any other bones of the skull. They under- 
lie and embrace the inferior edge of the ethmo-presphenoidal region of the basis cranii, 
and, in all birds in which they are distinctly developed, except the Ostrich, they are 
connected behind with the palatine bones. In most birds they early unite into a 
single bone; but they long remain distinct in some Coracomorphe, and seem to be al- 
ways separate in the Woodpeckers.” é 
I have found it in numerous adult specimens of the common fowl, but it is a rare 
* coincidence to ever find it in the crania of museum collections. I have in my section 
at the United States National Museum, the “Darwin types” of the skulls of the wild 
