388 Annals of the Carnegie Museum. 



EXPLANATION OF PLATES. 



(All the figures in the plates are reproductions of photographs made by the 

 author of the specimens described.) 



Plate XVL 



Fig. I. Superior view of the skull of the " Cahow." McGall Coll., nat. 

 size; adult; imperfect (right zygojna lost, etc.). Some of the matrix still 

 seen adhering to it, between the orbits and in the nostrils. Lower mandible 

 removed. Either lacrymal coossified at the side of the skull and the suture 

 obliterated. 



Fig. 2. Same view of the skull of another individual of the same species 

 as shown in Fig. i; nat. size; adult. McGall Coll. Imperfect. Mandible 

 removed. 



Fig. 3. Same view of the skull of still another individual of the same spe- 

 cies (" Cahow ") as shown in Figs, i and 2 ; nat. size ; adult. McGall Coll. 

 Imperfect. Mandible removed. The three crania shown in Figs. 1-3 show 

 how little individual variation exists, as a rule, in this part of the skeleton 

 of the " Cahow." The shortest line between the supraorbital glandular de- 

 pressions is, however, seen to vary to some extent. 



Fig. 4. Basal view of the cranium of a " Cahow," nat. size ; adult. McGall 

 Coll. Mandible removed, and the pterygoids and quadrates missing. Vomer 

 coossified with palatines. 



Fig. 5. Right lateral view of the skull of a " Cahow," with mandible — the 

 latter doubtless from a different individual. Nat. size ; adult. Coll. Amer. 

 Mus. of Nat. Hist. Quadrates were probably from another specimen, while 

 the pterygoids are missing. 



Fig. 6. Right lateral view of the skull and mandible belonging to a 

 skeleton in the collection of the U. S. National Museum labeled " Puffinus 

 ohscurus " (No. 17724, Bermudas, C. Mailer, collector). 



