Vol. XV.-] <,uvvKiA)i,()steul(>!iv of Jhinis'i, Coniiontnl. 8? 



refer. As he iu no way refers to llie skull of Niinnoptcntm in his 

 article on its osteology, 1 shall dispose of tlial important part of 

 the skeleton before so doing. 



During the past thirty years I have published a number of 

 papers on the osteology of the PhalacrocnracidcB, the most formal 

 one being a memoir on the subject, entitled " The Osteology of 

 the Steganopocies" (Mem. Carnegie Museum, No. .^,), in which a 

 very full account is given, illustrated with numerous plates of 

 theskeletons of quite a numlier of existing and extinct Cormorants 

 from various parts of the world. Since that memoir was pubhshed, 

 however, the number of Pbalacrocoracine skeletons in the collec- 

 tions of the United States National Museum has been substantially 

 increased, and there are now to be found, among other valuable 

 additions, no fewer than five more or less com})lete skeletons 

 of Nannopteriim. These, with others of the Phalacrocoracidce, 

 have been placed at my disposal by that institution for the 

 purposes of description. For this courtesy I am much indebted, 

 and in connection theiewith I have to thank Dr. Charles W. 

 Richmond and Mr. J. H. Riley, of the Division of Birds of the 

 Museum, for their kindness in transmitting me this valuable 

 material. 



I find, in addition to the five skeletons of Harris's Cormorant 

 reff^rred to above, those of P. carbo, P. pundatns, P. auritus, P. 

 iirile, P. magellanicus, P. penicillatus, P. vigua, P. albiventris. P. 

 pelagicus. P. perspicillatus, and others. 



The Skull (see figures on Plate XV.)— All the skeletons at hand of 

 this Cormorant belonged to fully adult individuals, but un- 

 fortunately the sex of no one of them is recorded. Their Museum 

 numbers run — 19,628, 19,719, 19,720, 19,721. and 19.722, which 

 last is without a skull. 



Measured in a straight line from the apex of the superior 

 mandible to the most posterior point on the occipital condyle, 

 the skull numbered 10,719 has a length of 162 miUimeters ; 19,720, 

 of 160 mm. ; 19,721, of 164 mm. : while the one numbered 19,628, 

 which certainly belonged to an old bird, measures in length 

 but 147 mm. Disregarding this last skull, the average length 

 of the skull of this Cormorant, based on the measurements of the 

 first three, would be 162 millimeters. 



Apart from these less important, though longer, transverse 

 cranial diameters, and selecting the one of the brain-case at its 

 widest part for comparison, skull No. 19,719 has a maximum 

 width, through the broadest part of the parietal region, of 

 32 millimeters ; 19,720, of 32 mm. ; 19,721, of 32.5 mm. ; while 

 19,628 measures but 30 mm. In the frontal region, superiorly, 

 the shortest distance between the orbital peripheries in the first 

 three skulls measures 18 mm., while in No. 19,628 the same trans- 

 verse diameter measures but 13.5 mm. (See fig. i, Plate XV.) 



Unless there be a sexual difference here, this is a remarkable 

 case of individual variation in the matter of size, especially when 

 skull No. 19,628 belonged to a very old bird, and one with an 



