CONTEIBUTIONS TO THE NATURAL HISTORY OF THE 

 COMMANDER ISLANDS. 



XI. THE CRANIUM OF PALLAS'S CORMORANT. 



By Frederic A. Lucas, 



Curator of the Depariment of Comparative Anatomy, 



In 1882 Dr. Leoiiliard Stejneger^ obtained from a uatural boue de- 

 posit on Bering Island a small number of bones of Pallas's Cormorant, 

 Phalacrocorax persineiUatus. During the summer of 1895 Dr. Stejne- 

 ger again visited Bering Island and obtained from the same deposit a 

 second lot of bones, the most important of which were a cranium and 

 sternum. 



The cranium (No. 19417, U.S.N.M.), or, strictly speaking, the calva. 

 rium, in its general contour most closely resembles that of P. penicil- 

 latus among existing cormorants, but is decidedly larger, and is pro- 

 portionately wider than in that species, while the beak is shorter. As 

 far as mere size is concerned, the skull of an adult male of P. carho 

 would be as long as that of P.jyerspicillatHS, but the latter is much wider 

 and is more depressed. The cranium is readily distinguished from that 

 of I\ urile by its greater size and less depression, and by having a pro- 

 portionately stouter beak, whose ridge lacks the slight but character- 

 istic emargiuation found near the base of the beak in P. itrile. 



As a matter of fact, the differentiation of cormorants into sj^ecies 

 with grooved beaks and those without does not exist, so far as the 

 bony beak is concerned. Some have deeper grooves than others, but 

 all have more or less of a furrow along the side of the mandible, and 

 there is every degree of gradation, from such well-furrowed beaks as 

 those of P. albiventris and P. magellanicns to the shallow grooves of 

 P. melanoleucus and P. carho. 



'Proc. U. S. Nat. Mus.. XVII, 1889. pp. 83-94. 



rroceedings of the United States National Museum. Vol. XVIII— No. 1095. 



717 



