9G0 MR. w. p, prcRArT on the [Dec. 13, 



the lateral expansion of the wing is "3 in. and the fossa is wider than 

 that in the two preceding lorms. In Megadypfes antipodum this 

 region of the fossa is both deep and wide, and the squamoso- 

 parietal wings are well developed, maki'ng this region of the skull 

 closely reseiiible that of Eiahjptula (PI. LX. fig. 5). 



Fygoscelis resembles Caiarrhactes in the formation of this region 

 of the skull. In the shape of the cerebellar dome, in its greater 

 width and cm'\ature in profile, it approaches C. sddcgeli. The 

 squamoso-parieta) wings are but feebly devetoped, being represented 

 only by a low ridge. F. adclice differs from P.jxqma in the outline 

 of the cerebellar dome, inasmuch as in the latter the curve continu- 

 ally increases till it ceases at the foramen magnum. 



In Aptenodytes the squamoso-parietal wings are more feebly 

 developed even than in Fygoscelis. In A. forsteri they scarcely 

 extend halfway to the lambdoiclal ridge. 



Eudyjjtulu, in the form of the cerebellar dome, is somewhat 

 intermediate between C. chvysocome and C. cJirysolojjlius. In the 

 development of the squamoso-parietal \^ings, and the width of the 

 fossa posteriorly, it surpasses both. Though the vertical height 

 in both genera is relatively the same, in Exidypttda the wings are 

 further remoA^ed from the cerebral dome ; in E. minor they are bent 

 forward superiorly so as to join this almost at a right angle. In 

 E. alhosiguaia tliny run up to join the suj^ra-occipital or lamb- 

 doidal ridge — which lies, really, halfway between the suture of 

 that name and the coronal suture — where they remain separated 

 by some "6 in. 



Sp)heniscvs demersas differs from ^. mayeUanicns in that the 

 temporal fossa, posteriorly, does not actually reach the vertex of 

 the skull : the squamoso-parietal wings are coutiiuied from the 

 top of the fossa forwards as a narrow and low ridge, eventually 

 joining a median sagittal crest running forwards on to the cerebral 

 dome. In S. mageUanicvs this region of the fossa runs upwards 

 to the vertex, terminating at the sagittal I'idge, being accompanied 

 throughout by the squamoso-parietal wings. 



In all the genera the exoccipitals are produced downwards, on 

 either side, into a short, blunt, paroccipital process. The free edge 

 of this, in Caiarrhactes, is longer than that of the squamosal 

 prominence; in Fygoscelis these relations are reversed. In Apteno- 

 dytes, Eudyj^tida, and Spheniacus these processes are subequal. 

 The paroccipital processes form the outer wnWs of a large 

 pneumatic caAity lying between the procitic and exoccipital, which 

 opens into the mouth of the tympanic cavity. 



In the skull of tlie nestling Splicniscus the form and position 

 of the squamoso-parietal wings closely resemble those of Catar- 

 rJiacies. The posterior region of the temporal fossa, so remarkable 

 for its depth and width in the adult, is in the young bird very 

 shallow and widely separated fi'om its fellow of tlie opposite 

 side. 



The Foof of the SlidL — This is formed by the frontal and parietal 

 bones. The posterioi* region of the cranium, in all the Sphenisci, 



