154 MEMOIRS OF THE CARNEGIE MUSEUM 



of a long and narrow V. The ramal sides are not deep ; there is no ramal vacuity ; 

 and the bone gradually tapers to a sharp point in front. From the nature of the 

 splenio-dentary articulation the thin bones being feebly wedged together there 

 the mandible is of a consequence very weak at that point. A considerable symphysis 

 exists, with the barest rudiment of a median, inter-ramal spine present. For the 

 most part, the upper and lower borders of the bone are rounded, though the supero- 

 dentary edges, from sphenial articulation to apex are inclined to be cultrate. Either 

 coronoid process is very much reduced, while between it and the articular cup for the 

 quadrate, on the mesial aspect of the ramus, is a long foramen of an ellipsoidal 

 outline, entering the inner structure of the jaw. Each hinder end of the mandible 

 is, as usual, constructed to articulate with a corresponding quadrate. On the upper 

 side of one there is a deep, rather narrow, obliquely-placed cup its mesial end 

 being the anterior one. This is for the inner articular facet of the foot of the quad- 

 rate. In front of this is a small, nearly flat, articular surface, and it is for the outer 

 facet of the quadratal foot. Facing directly forward, and standing on the postero- 

 internal edge of the cup is still another small facet, intended for a corresponding 

 one on the same bone. These articular cups develop no inturned mesial pro- 

 cesses, but the usual pneumatic foramen is present. The articular processes standing 

 out behind, are of good size, of a quadrilateral form, and so twisted that the lateral 

 surface in either case looks slightly upward and, to a much greater degree, outward. 



Of the Axial Skeleton. Endowed as it is with special points of interest, much has 

 been written upon this part of the anatomy of Anhinga. It has been touched upon 

 with greater or less elaboration by Brandt (Mem. de 1'Acad. Imp. Sci. de St. Peters- 

 bourg, torn, v., 6 ime Serie, Sect, de Sc. Nat., 1839), by Mivart, in his memoir in the 

 T. Z. S., already cited, by Garrod (Coll. Sci. Mem., p. 334), by Donitz (Archiv fur 

 Anat. u. Phys., 1873, p. 357), and by Hunter (Essays and Obser., 1861, v. 11, p. 

 328), and by others. Most of these writers have been attracted by the peculiarities 

 seen in the spinal column, which I will now proceed to examine. 



In the atlas we find the articular cup of the condyle perforated near its upper 

 border. Its neural arch is nearly as deep as it is wide, and from it projects behind, 

 upon either side, a conspicuous little spine. The small hyapophysis of this vertebra 

 also projects posteriorly beyond the centrum. From the axis to the seventh inclu- 

 sive, the vertebrae are especially notable for being of no great caliber in point of size, 

 and at the same time remarkably elongated. A low, sharp neural ridge and hyapo- 

 physial spine characterize the axis. Its postzygapophysial part is welded into a 

 common plate of bone, with the articular facets upon its under side. Upon its 

 ventro-posterior aspect an open channel is formed by a curling downwards of bone 



