1898.] OSTEOLOGY or BIRDS. 97 



E. Pectoeai. Limb (figs. 5-7, p. 90). 



A. All the bones of the wings pneumatic. 



a. Ulna with a large nneumatic foramen lying ou the palmar surface distad 



of the glenoid cavity. 



a'. Humerus nearly as long as the ulna (in the articulated wing the arm is 

 nearly as long as the forearm). Sub-trochautei-ic I'ossa large, continued 

 eephalad under capitulum of humerus as a large pneumatic foramen, 

 into which open numerous small foramina. Crista inferior (ulnar 

 tuberosity) with anterior surface much inflated, and sharply defined 

 from the shaft, distad, by a groove. Coraco-humeral groove a shallow 

 depression. Pectoral crest (radial tuberosity) triangular, of moderate 

 size. Insertion of brachialis anticus well-defined ; with a pneumatic 

 foramen above condylus ulnaris. Eadius with a faint depression 

 over the dorsal aspect of the expanded distal end. Manus having the 

 carpo-inetaearpus three times the length of Ph. 2. D. II. Ph. 1. D. II. 

 with two deep and sharply defined postaxial depressions. Ph. 1. D. III. 

 with a well-marked trian gular postaxial border Pelecanus. 



h'. Humerus about one-fifth less than the ulna (in the articulated wing the 

 arm is less than the forearm). Sub-trochanteric fossa not overhung 

 by tuberculum inferius, otherwise resembling that of Pelecanus. 

 Crist a inferior inflated, but less sharply defined from the shaft. Coraco- 

 humeral groove deep and narrow ; triangular form of the i-adial 

 tuberosity (pectoral crest) very large. Depression for brachialis 

 anticus with a pneumatic foramen proximad of radial condyle. 

 Eadius with a deep depression over the superior border of the distal 

 articular end. Manus having the carpo-metacarpus little more than 

 twice length of Ph. 2. D. II. Postaxial ledge of Ph. 1. D. II. with 

 two shallow depressions. Ph. 1. D. III. with the triangular postaxial 

 border slightly developed Fregata. 



b. Ulna with a very shallow depression in place of a pneumatic foramen. 



Humerus less than ulna (in the articulated wing the arm nearly equals 

 forearm). Sub-trochanteric fossa overhung by tuberculum inferius, and 

 running up as a pneumatic foramen into the caput humeri. Crista 

 inferior flattened, passing gradually into the shaft. Coraco-humeral 

 groove deep. Pectoral crest triangular, size moderate; depression for 

 brachialis anticus not well-defined, without a pneumatic foramen. 

 Manus having carpo-metacarpus less than twice length of Ph. 2. D. II. 



Phaethon. 



c. Ulna with a distinct palmar and interglenoid pneumatic fossa. Humerus 



longer than ulna (in the articulated wing the arm is one-fifth longer than 

 forearm). Sub-trochanteric fossa overhung by tuberculum inferius and 

 running up as pneumatic foramen into caput humeri. Crista inferior 

 slightly swollen, moderately defined from the shaft. Coraco-humeral 

 groove shallow. Pectoral crest in the form of a long low ridge but 

 little raised above the shaft. Depression for brachialis anticus well- 

 defined and without a pneumatic foramen. Metacarpus nearly or 

 quite as long as Ph. 2. D.II -SMfo- 



B. Wing-bones not pneumatic : pectoral crest a low ridge. 



d. Cri.=,ta inferior passing insensibly into shaft. Sub-trochanteric fossa deep, 



pneumatic foramen absent. Ulna equal or nearly equal in length to the 

 humerus Cin the articulated wing the arm shorter than forearm), with the 

 border of the glenoid cavity for the radial condyle of the humerus 

 produced into a hook-like process. Manus much shorter than ulna. 

 Mc. III. very slightly arched ; Ph. 1. D. II. with a deep ventral fossa. 



Phalacrocorax. 



e. Crista inferior with its free border arched, distinct from shaft, with 



a slight depression in place of the sub-trochanteric fossa. Ulna shorter 

 than humerus (in articulated wing forearm shorter than arm) ; hook- 

 like process of glenoid cavity of radial condyle of humerus but slightly 

 developed. Manus equal, or nearly equal, to that of ulna. Mc. III. not 

 arched ; Ph. 1. D. II. with a shallow ventral depression Plotv.i. 



Pboc. Zool. Soc— 1898, No. VII. 7 



