OCR Text |
Show 1899.] OSTEOLOGY OF THE TUBINARES. 387 The antorbital plate of Pelecanoides resembles that of the Diomedeidas, but is narrower and does not quite reach to the level of the lachrymal. The olfactory cavity is of great size in all the Tubinares except Pelecanoides and Puffinus assimilis; in these it is reduced to a chamber of comparatively insignificant size. The lachrymal is of very considerable size and more or less T-shaped. It extends from the fronto-nasal region downwards to the quadrato-jugal bar. The stem, anteriorly, is provided with a large lachrymal foramen. In CEstrelata and Thalassceca the posterior limb is laterally expanded and rises upwards, its free edge looking outwards and backwards. In Priofinus this peculiarity is repeated, but in a less marked degree. Ossifraga, Procellaria, Oceanites, Cymodroma, Pelagodroma, and Bulweria all agree in having the anterior limb produced far forwards, so much so that the horizontal exceeds that of the vertical axis, the former being represented by a line traversing the arms, the latter the stem. In Cymodroma, Oceanites, and Pelagodroma there is a wide chink separating the dorsal border of the anterior limb from the fronto-nasal border. In Pelecanoides the anterior and posterior limbs are almost obsolete, the anterior limb is pierced by a large foramen, and the inner, nasal border is notched. The vacuity in the stem of Puffinus assimilis is very large. In the Diomedeidas the anterior and posterior limbs, as in Pelecanoides, are freely developed. In Diomedea melanophorus the anterior is wanting. In Phcebetria the posterior limb is produced outwards, backwards, and upwards more than in any other member of the order. The lachrymal is ankylosed with the nasal in Ossifraga, Fulmarus, Daption, Prion, Thalassceca, CEstrelata, aud Priocella. The ossiculum lachrymo-palatiuum, or " os crochu," is best developed in the Diomedeidas. In Diomedea exulans it is a styliform bone, the upper half of which is of a more or less triangular spatulate form ; the lower is cylindrical. Seen in situ, from in front, the inner border is concave, the outer triangular. It articulates above with a process from the inner border of the lachrymal, by means of its laterally compressed dorsal extremity, and below by a ligament to the outer border of the palatine. In Thalassceca, Prion, Bulweria, and Priofinus it is represented by a small slender rod, which in the first-mentioned is almost hairlike in thickness. In both it depends from the distal end of the lachrymal below its junction AAith the antorbital plate, and extends downwards towards the palatine, Avith which, doubtless, in life it is connected by ligament. In all the other specimens under my charge it is wanting. The late W . A. Forbes (6) gives a brief survey of this bonelet and its relations to the various surrounding parts. In many cases it is represented only by a vestigial nodule imbedded in ligament. It occurs also, according to Forbes, in the " Musophagidas, many Cuculidas, Ghunga, and Gariama, as well as |