OCR Text |
Show 1899.] OSTEOLOGY OF THE TUBINARES. 405 G R O U P 0. Supra-orbital grooves deep and wide, sharply defined, and tending to meet in the middle line ; ptej*ygoids rod-shaped, with articular surfaces for the basipterygoid processes-which are often vestigial; vomer more or less boat-shaped, not cleft more than half its length; length of anterior nares never more than £ that of upper jaw. a. Lachrymal free. a'. Supero-external angle of antorbital plate incomplete, forming with the lachrymal a large foramen Puffinus. Priofinus. Majaqueus. b'. Supero-external angle of antorbital plate complete, closing the space between itself and the lachrymal Bulweria. b. Lachrymal anchylosed with nasal. c'. Size very large; basioccipital with well-developed mammillary processes ; a large space between the dorsal border of the antorbital plate and the frontal; postorbital processes turning downwards and ending in a point; lachrymal with the horizontal greatly exceeding the vertical axis ; quadrato-jugal bar with a strongly marked triangular process for articulation wi th the quadrate Ossifraya. d'. Size not exceeding 4 inches; basioccipital without mammillary processes ; postorbital processes with a squarely truncate outer border ; lachrymal with the horizontal and vertical axes about equal; quadrato-jugal bar of uniform thickness throughout. a''. Interorbital region of frontals dividing supra-orbital grooves moderately wide; lachrymal with its postero-dorsal free edge produced laterally into a pair of conspicuous wings. a3. Vomer tapering anteriorly to a point; beak stout and wide, not conspicuously narrower at the tip ; anterior palatine vacuity very wide, not bounded by a flattened ledge on either side ; palatines elongated, ventral surface conspicuously keeled posteriorly. a*. Temporal fossa deep, nearly meeting in mid-dorsal line. Fulmarus. bl. Temporal fossa shallow, divided by the roof of a distinct cerebellar prominence Daption. b3. Anterior end of vomer more or less hidden by the maxillo-palatine processes, which meet in the middle line ; palatines short and broad, proximal end not conspicuously keeled ; anterior palatine vacuity narrow, bounded on either side by a flattened ledge ; beak more or less conspicuously depressed, the extreme form resembling that of Balaniceps Prion. c3. Vomer terminating anteriorly in a long spine ; palatines elongated; beak slender. c4. Anterior limb of free bifid end of lachrymal longest; interorbital region of frontals less than width of supra-orbital groove. Thalassceca. d*. Posterior limb of bifid end of lachrymal longest and directed backwards ; interorbital region of frontals much greater than width of supra-orbital grooves QHstrelata. . b". Supra-orbital grooves divided by a thin bony ridge ... Priocella. DlOMEDEIDjE. a. Interorbital region of frontals broad ; antorbital plate not extending outwards to the level of the outer margin of the lachrymal; with a well-marked tubercle lying between the mammilary processes. a'. Interorbital region of frontals not exceeding ir of the width of the frontals between the lachrymals; pterygoid ends of the frontals becoming abruptly wider in the region of a line drawn through the median palatine keel Diomedea. PROC. ZOOL. Soc-1899, No. XXVII. 27 |