1899.] OSTEOLOGY OF THE TUBrNARES, 387 



The antorbital plate of Pdecanoides resembles that of the 

 Diomedeidse, but is narrower and does not quite reacli to the 

 level of the lachrymal. 



The olfactory cavity is of great size in all the Tubinares except 

 Pelecanoides and Paffinus 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 (Estrelata and Thalassoeca the 

 posterior limb is laterally expanded and rises upwards, its free edge 

 looking outwards and backwards. In Prlofinus this peculiarity is 

 repeated, but in a less marked degree. Ossifraya, Procellaria, 

 Oeeanites, Gymod,roma, Pelagodroma, and Bidweria 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 C'ymodroma, Oeeanites, 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. Tlie vacuity in the stem of 

 Puffinus assimilis is veiy large. 



In the Diomedeidae the anterior and posterior limbs, as in 

 Pelecanoides, are freely developed. In Diomedea melanopliorus the 

 anterior is wanting. In PJioebetria 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 Ossifraya, Fulmarus, 

 Daption, Prion, Thalassoeca, (Estrelata, and Priocella. 



The ossiculum lachrym,o-ixdatimim, or " os crochu," is best 

 developed in the Diomedeidae. In Diomedea exidans 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 Priojinus it is represented 

 by a small slender rod, which in the first-mentioned is almost hair- 

 like in thickness. In both it depends from the distal end of the 

 lachrymal below its junction with the antorbital plate, and extends 

 downwards towards the palatine, with which, doubtless, in life it 

 is connected by hgament. In all the other specimens under my 

 charge it is wanting. The late W. A. Torbes (6) gives a brief 

 survey of this bouelet 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 

 " Musophagidse, many Ouculid^, Ohiinya, and Oariama, as well as 



