98 NATURAL HISTORY OF KERGUELEN ISLAND. 



are: two deep foss^just above and parallel to the superior orbital mar- 

 gins^ a promiuent bocy crest (for the support of the caruucle) iu front 

 of tliese, the large size and subcircular form of the foramen magnum— 

 all of which will be described in detail below. 



Occiintal bone is convex inferiorly and irregularly trapezoidal in 

 ehape. Its crest is less prominent than usual, although quite distinct; 

 shai>ed like a bow, with its extremities distinctly defined as far as the 

 superior border of the meatus auditorius externus. The condyle is small 

 and spherical (not nicked, as in GalUnce). Foramen magnum is nearly 

 circular iu outline, its anterior border being cut off so as to form a high, 

 broad ar^h. It measures in antero-posterior diameter 0,21, in trans- 

 verse, diameter 0.32 inch. On each side of the condyle is a broad space 

 for ligamentous attachments ; laterally and posteriorly to these its 

 paroccipital(?) portions extend downward as vaginal processes, protect- 

 ing th€ posterior border of the external auditory meatus. From the 

 foramen magnum to the crest extends upward a prominent median 

 ridge, flanked by lesser ridges on each side from the lateral portions of 

 the foramen. 



Sphenoid is irregularlj' pyramidal in shape, beingproduced forward into 

 a. long cultrate spine (basi sphenoid), embraced by the two prongs of the 

 vomer and upon which ride the palathie -awA pterygoid bones. There are 

 110 distinct basipterygoid processes. Only the marginal portions of the 

 basisphenoid contribute to the floor of the orbits, its orbital plates pass- 

 ing upward and outward to complete a septum between the brain and 

 orbit. This septum is perforated iu the median line by two irregular 

 foramina for the transmission of the optic and olfactory nerves. The 

 inferior (optic) foramen is heart-shaped, the apex of the figure being 

 directed upward, and the lateral lobes much prolonged. The superior 

 ((flfactory) foramen presents the outline of the ace of clubs. As these 

 are the chief anterior foramina of the brain-case, they probably transmit 

 oiLer nerves distributed to the orbit and face, as well as the olfactory 

 and optic. Rising from the superior margin of the basi-sphenoid is the 

 inter-orhital septum, perforated anteriorly iu this species by an irregular 

 vacuity, and posteriorly by an extension forward of the optic and ol fac- 

 tory foramina already noted. The interorbital septum is, hoy?ever, 



ridge very promincut ; * . * * * ridges for the attachment of the n)asseter mnscles 

 sinmsly marked." (Osteologia Avium, London, 18(57, ^. 176.) As we cauuot believe there 

 is any marked difference in the skulls of C. alba and C. minor, we simply fail to ap- 

 l>ieciate the pertiueuce of the author's remarks in this case. 



