VoL ^^^•■j Shufkldt, Osteology of Harris's Cormorant. gi 



tcrniinatcs, and wlune it docs tcnniuate in a young Connoraiit. 

 They are double in Nannoptcrum, and usually rather small. This 

 species may even have three such foramina on either side (No. 

 19,721, Coll. U.S. Nat. Mus.) They are large in PalUis's Cormorant 

 (No. 19,417, Coll. U.S. Nat. Mus.), and nearly as big in /•*. carbu. 

 Although I have not dissected a Cormorant lately, I would not be 

 surprised to Und that these several foramina transmitted ])oth 

 nerves and vessels to the structures of the superior mandible 

 beneath its theca ; but, even if this be so, it would not disprove 

 what has just been set forth as to their being at the same time the 

 remains of the narial apertures, and I must believe that they are. 



The plate of the mesethmoid in Nannopterum exhibits near its 

 centre quite a sizable vacuity. This opening, in the same 

 locality, is also present in the skul's of P. iirile (where it is very 

 large), P. auritus, and P. penicillatus, but is never found in 

 Pallas's Cormorant or in P. carbo — that is, in the crania of atlult 

 birds. 



In all Cormorants the presphenoid exists as a conspicuous keel, 

 co-ossified in the middle line on the ventral aspect of the brain- 

 case, extending from the basitemporal to a point above the 

 pterygo- palatine articulation, from which point, as a straight, 

 narrow bar, it bounds the immense interorbital vacuity below, 

 till it merges, anteriorly, with the mesethmoid, projecting in front 

 of the latter as a prominent, sharp spinelet. Sometimes the floor 

 of the cranial casket, upon one side or the other of this sphenoidal 

 keel, may be so thinned as to have, as a result, a vacuity of some 

 size remain in it. This is the case in the skull of one of the speci- 

 mens of Harris's Cormorant (No. 19,628), also in P. penicillatus 

 (No. 940), where it is much smaller. In P. carbo the floor of the 

 brain-case in this locahty is very much thicker than it is in the 

 two Cormorants just mentioned, and no such foramen is ever 

 left there after cranial ossification is complete in the adult. In 

 all Cormorants the basitemporal area is small and concaved. 

 These birds have the osseous chamber of the ear much exposed, 

 and a free, bony siphonium leads into it upon either side. 



The massive quadrates, the big pterygoids with their sharpened 

 superior borders, and the large, posteriorly-fused palatines, are 

 all so well seen in fig. 5 of Plate I. of this paper that it would be 

 superfluous to give any detailed description of these parts. 



With respect to the mandible in Nannopterum (figs. 2 and 4, 

 Plate XV.), the bone presents the same general pattern we find it 

 to possess in Cormorants at large, and this has been quite fully 

 described in my " Osteology of the Steganopodes " (p. 169). 



In P. carbo the distal symphysial part of the mandible is con- 

 spicuously bent down (No. 18,851, Coll. U.S. Nat. Mus.), which 

 is not the case in any other Cormorant before me at this time, 

 including Harris's. 



In my description of the skull of Anhinga anhinga {loc. cit., 

 pp. 151, 152, figs. 3, 4, sr. m.), I gave a short description of a bone 

 found articulating with the distal extremity of the maxillary. 



