1888.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. o05 



As already mentioned above, there are eight free vertebrae in the 

 tail, and a large pygostyle. The neural spines of these vertebne are 

 short and stumpy; some of them are bind anteriorly ; the neural arches 

 beneath them close over the spinal canal for the entire length of the 

 series, and it is seen to perforate, for a short distance, the pygostyle. 

 The transverse processes are unusually thiek and strong, being gen- 

 erally depressed, and in those segments where chevron bones occur they 

 are auchylosed to the centra and hook forward over the preceding 

 vertebra, alter a fashion. of many other birds wherein they are found. 



On either end of any of the centra the facets show but little con- 

 cavity or convexity. 



The pygostyle (Fig. 37) appears to be composed of about six vertebra 1 , 

 of which the three anterior ones can be quite easily made out. It has 

 a very unusual form in this bird, being very long and subcorneal, with 

 sharp superior border and rather decurved apex. Below, it is broad 

 and somewhat convex. Viewing it from in front we notice that it has 

 all the elements present, though in a very rudimentary state, of one of 

 the caudal vertebne, including a large, prominent, and auchylosed 

 chevron bone. 



OF THE APPENDICULAR SKELETON. 



The pectoral limb. — We find the bone of the brachium to be somewhat 

 longer than the radius aud ulna in this limb, but the material before 

 me will not permit me to say whether or no this holds true with Cor- 

 morants aud Pelicans. In it the ulnar crest is prominent and project- 

 ing, though rather inclined to retreat from the elongated and shallow 

 pneumatic fossa than arch over it, as in many other water birds. The 

 radial crest is reduced to a long, low, inconspicuous ridge, aud, in fact, 

 this proximal end of the humerus, as a whole, merges into the shaft so 

 gradually from both sides, and its being so narrow withal, that we are 

 rather impressed with its lack of strength and an absence of a certain 

 robustness so characteristic of other birds of equal size that lead a simi- 

 lar life. This in no way applies, however, to the shaft itself, for this 

 subcylindrical aud hollow bony tube, with its double sigmoidal curve, 

 carries with it the very elements of strength and power. 



Its distal extremity lacks but little of being as wide as the widest 

 part of the head of the bone. It is without an ecto condyloid process, 

 has the trochlea' very prominent, and presents for examination a deep 

 fossa to the anconal side of the ulnar tubercle. 



The shaft of radius for so long a one is unusually straight, aud only 

 a slight curve is noticed in the proximal moiety of ulna. 



In its continuity the former bone is subtrihcdral in its form, with its 

 pneumatic foramina situated beneath the transversely expanded portion 

 of the distal end. Muscular lines mark this radial shaft along its in- 

 ferior aspect. 



Por its distal moiety the shaft of ulna is nearly cylindrical in form, 

 rroc. K M. 88 — 20 >A£ji**3 " 



