BHUFELDT.] OSTEOLOGY OF THE TETRAONIDA. 663 
the otocrane, one into the cranial cavity, and one leading through the 
basi-sphenoid to the base of the “sella turcica” at the carotid opening ; 
they transmit principally the eighth nerve and the internal jugular and. 
branches. 
In some of the very old individuals of the Tetraonine quite a strikin 
characteristic presents itself in the capaciousness of the opening to the 
otocrane, produced by a thin, wing-like expansion, recurved forwards, 
formed by the outgrowing and union of the centrum of the second 
vertebra and the diapophysis of the first. This feature is not particu- 
larly noticeable in the Ortygine, nor in Lagopus, Cupidonia, and Bonasa, 
still less so in the Sharp-tailed Grouse, among the Tetraonine, but quite 
marked in old males, especially in Canace and Centrocercus (Figs. 52, 
74, 88, and 89). No very decided differences exist among the Grouse 
with regard to the foramen magnum and the occipital condyle; the 
former is universally of good size for its owner, subcircular, and with- 
out any encroachments upon its margins beyond the condyle. This lat- 
ter, always sessile, reniform in contour, occupies its usual position below 
the foramen, with its long axis placed horizontally. In all the Grouse, 
save Canace and Centrocercus, it slightly invades the marginal periphery 
of the great foramen of the occiput, and in all the excepted genera is 
more or less shortened transversely. 
The second cranial segment constitutes the parietal vertebra, and its 
elements are shown in the same plate, Fig. 51, where indicators pass 
through its neural and hemal arches, P. V. and P. V’: P. V is the mes- 
encephalic arch, constituted in the complete cranium by the bones P,. 
the parietal or neural spine, when linked with its fellow; a. s., the alis- 
phenoids, the neurapophyses ; m. s., the mastoids, the diapophyses ; and 
to quote the following from him. In summing up the various parts of the temporal 
bone, he says: 
The following is a list of these morphological elements : 
1. Squamosal. A membrane bone with which in mammals the maxilla is connected by the malar and 
the mandible is directly articulated. The ‘‘squamous portion” of the temporal. 
2. Tympanic. Accessory to the organ of hearing, forming the meatus auditorius externus. The 
‘‘anditory process.’ 
2 Danan bat Primitive otic elements together forming the periotic or petro-mastoid ; the oto- 
2 ata: crane or bony capsule of the organ of hearing, inclosing the bony labyrinth, 
5. Obisth-otic developing the mastoid cells, and practically constituting the ‘‘petrous” and 
aie “‘mastoid”’ parts of the temporal, i 
6. Malleus, the proximal end of the mandibular 
6. Mallens. Ossicula aditus or phonophori arch ; 
7. Incas. } in man devoted to audition, , 7. Incas, the proximal end of the hyoidean arch. 
8. Stapes. but | 8. Stapes, connecting fenestra ovalis with the 
" Byoidean arch. oer , 
'ympano-hyal not recognized in human anat- 
in ay qa Uypl } Blements of the hyoidean arch. ; omy. 
Raita drat acaad Stylo-hyal, the ‘‘styloid process.” 
This does not include the 0s orbiculare, a minute ossification occurring at the junc- 
tion of the incus with the stapes, and in man for a short time separate. 
Still further on this author states: ‘‘ The periotic develops from a mass of cartilage 
situated in the basis cranii between the occipital and sphenoid from three centers of 
ossification, which, however speedily and completely they may coalesce, as they do 
in man before birth, represent as many distinct bones, one or more of which may re- 
main separate in many animals. These are the prodtic, the epiotic, and the opisthotic. 
The first of these is anterior and in special relation with the corresponding vertical 
semi-circular canal. The second is superior and external. The third is posterior and 
inferior in relation with the posterior vertical semi-circular canal. Their confluence 
completes a bony periotic capsule, inclosing the labyrinth or cavity of the inner ear. 
This is the triune periotic bone; with its mastoid developments the still only triune 
petro-mastoid bone; with its tympanic annex the otocrane, or skull of the ear, contain- 
ing the essential parts of the organ of hearing. The periotic proper corresponds 
closely enough with the ‘ petrous portion of the temporal” of human anatomy—the 
‘‘netrosal bone,” as it is sometimes called. (The Nature of the Human Temporal 
Bone, Am, Jour. Otology, vol. iv, Jan., 1882, pp. 25-29.) 
