Vol. XV. I Shvfki^dt, Osteology of Harris's Cormorant. 105 



thus articulated tlie shafts ol the coracoids, in the case of Harris's 

 Cormorant, come witliin a few degrees of being parallel to each 

 other (Nos. 19,628 and 19,722). This degree of parallelism varies 

 for different individuals, but it can be estimated ; for example, 

 if we draw a transverse line through the " feet " of the coracoids 

 when they are normally articulated, then extend the lines of 

 their longitudinal axes until they meet below the sternum, we 

 will find that, from their point of meeting to the middle of the line 

 drawn between the coracoidal feet, they have a length of some 

 y^ millimeters. A corresponding line, in the case of P. urile 

 (No. 19,655, Coll. U.S. Nat. Mus.), measures but 45 millimeters — 

 the intersection of the extended imaginary lines, prolonging the 

 longitudinal axes of the coracoids of this species, being opposite 

 the posterior termination of the keel of the sternum on that bone. 

 This goes to how that the angle formed by the extended longi- 

 tudinal axes of the coracoids in Nannopterum harrisi is much 

 more acute than it is in such a Cormorant as P. urile, and, con- 

 sequently, the approach to parallelism is just so much the nearer 

 in the former bird. They are, however, never absolutely parallel 

 any more than are the articulated scapulae, for when we extend, 

 by imaginary lines, the long axes of the blades of the latter, when 

 those bones are normally articulated in the skeleton, the point 

 of intersection of those lines is posterior to them at a point about 

 opposite the second caudal vertebra. 



The Appendicular Skeleton. 



The Pectoral Limb (fig. 25, Plate XIX.) — -Harris's Cormorant has 

 the skeleton of its wing quite as perfectly formed, and has in it 

 just as many of the bones as has any other Cormorant known to 

 me ; it simply has suffered great reduction in size. Dr. Gadow 

 has demonstrated that it has been " reduced to less than one-half 

 of its normal size " (p. 171). As a matter of fact, the skeleton 

 of this wing has all the appearance of one that might easily, 

 without any alteration whatever, belong to some small species of 

 Cormorant about the size of a Hooded Merganser {Lophodytes 

 ciiciillatiis). This has nothing to do with the characters the bones 

 present, for the wing of Nannopterum is wholly Cormorant in 

 particular and steganopodine in general. It is completely non- 

 pneumatic, as is the case of the wing-skeleton in most all ordinary 

 Cormorants. The humerus in P. auritus is an exception, for it 

 is certainly pneumatic in that species (No. 19,262, Coll. U.S. Nat. 

 Mus.), while it is never so in P. urile, but may be in P. carho. 



The pneumatic fossa of the humerus belonging to the skeleton 

 of Harris's Cormorant (No. 19,628) is shallow and elongate, ex- 

 tending down the ulnar side of shaft for a distance of 20 mm., 

 narrowing all the time until it merges upon the same at a point 

 opposite where the radial crest terminates on the other side of 

 the bone. 



On the palmar aspect of this humerus, just within the proximal 

 part of the radial crest, there exists a considerable concavity. 



