1899.] osTEOLOGt 6y the tubixaues. 411 



fosBse, the backward position of the squamoso-parietal wings, the 

 sagittal crest, coronal ridge, and large supraorbital grooves and 

 lachrymals. 



Kg. 2. The skull of Prio7i viftatus, nat. size (p. 389), to show the great de- 

 velopment of the upper jaw, the form of the supraorbital grooves, 

 the cerebellar prominence, teuiporal fossae, and fused lachrymals. 



Fig. 3. Skull of Proceliaria pdagica, nat. size (p. 404), to show the feebly- 

 developed supraorbital grooves and the great width of the inter- 

 orbital region of the fronlals. 



Fig. 4. The skull of Cymodroma melanoga&ter, nat. size (p. 404), to show the 

 form of the supraorbital grooves, the spine-like wings of the free end 

 of the squamosal, and the lachrymals, which are partly separated from 

 the frontals by a space. 



Fig. 5. The skull of an Albatross, Biomedea exulans, | nat. size (p. 404), to show 

 the great size of the supraorbital groove and ledge, and the shallow 

 femoral fossae, confined to the lateral surface of the cranium. 



Fig. 6. Tiie skull of Oceanites oceanicus, nat. size (p. 404), to show the form of 

 the supraorbital grooves. 



Plate XXIII. 

 Additional Letters. 



a&.=aliaphenoid. wi.^r meatus iuternus. 



a.o.p. =antorbital process. «i«s. = mesethmoid. 



a/ti;.=antrum of Highmore. op. = opistbotic. 



an.h.— „ „ „ ^. = parietal. 



6.p. = basipterygoid process. pa.=palatine. 



6i;./i. = basiteuipi)ral platform. par., pr. =zparasphenoid. 



ft.s.=basisphenoid. ^H.ap.= pneumatic aperture. 



C.J. y.= cerebral vein. ^:)ro. = pro6tic. 



e«(.^. -|-^».ap. = Eustachian groove -f- /;<. = pterygoid. 



pneumatic aperture. s.o. =supraoccipital. 



ep.o. = epiotie. s.s. = squamosal spine. 



ea'. = exoccipital. sj.= squamosal. 



_/;/.= floccular fossa. <.r.= temporalis recess. 



/r.=frontal. ■y= vomer. 



A.p^.=hemipterygoid. v./'. = vagus foramen. 



Fig. 1. Lateral aspect of skull of nestling Oceanodroma leucorrhoa, outer view, 



x2 (p. 393), to show the unclosed sutures. 

 Fig. 2. Lateral inner view, longitudinal section, of same skull (fig. 1), x2, 



to show unclosed sutures. 

 Fig. 3. Dorsal aspect of palatines, pterygoid, and vomer, x 2 (p. 39(j), to show 



the Ibrm and relations of the hemipterygoid. 

 Fig. 4. Lateral aspect of a portion of fig. 3, x3, outer view, to show relations 



of hemipterygoid. 

 Fig. 5. Ventral aspect of Pelecanoides garnoti, nat. size (p. 383), to show the 



form and great size of the basitemporal platform. 

 Fig. 6. Dorsal aspect of the vomer and neighbouring parts of the skull ol 



Biomedea exulans, |- nat. size (p. 390). 

 Fig. 7. Lateral aspect of same dissection as fig. 6, to show form of vomer, 



^ nat. size (p. 391). Note in figs. 6, 7, and 8 the antrum of 



Highmore. 

 Fig. 8. Ventral aspect of skull of Biomedea exulans, to show the schizognathous 



palate, | nat. size (p. 390). 



