EEMAINS OF FOSSIL PORPOISES KELLOGG 



23 



the vertebral margin, is missing. The external surface of this bone 

 is slightly concave posterior to the spine, indicating a shallow post- 

 scapular fossa. The prescapular fossa is widest near the medial angle 

 and rapidly narrows as it approaches the acromion process. The 

 inferior margin of the scapula is divided into two deep notches by the 

 long flattened acromion process. This process is relatively wide, ex- 

 panded and irregularly rounded distally, and slightly twisted. In 

 contrast to /ma, there is no distinct metacromial projection, and the 

 coracoid process is relatively long and attenuate. This coracoid 

 process (pi. 6, fig. 4) is inclined inward and directed downward from 

 the head of the scapula. Orcella possesses a long coracoid process, 

 but it is expanded distally. The neck of this scapula is rather broad 

 and the glenoid cavity for the head of the humerus is shallow. What 

 remains of the axillary margin shows that it turns abruptly back- 

 ward near the level of the upper margin of the acromion process. 



Measurements of the scapula, {in milUmeters) 



Measurements 



EurJiino- 

 delphis 

 bossi 1 



In in 

 geoff- 



Antero-posterior diameter of head of scapula 



Eitcro-internal diameter of head of scapula 



Posterior margin of head to tip of coracoid process 



Posterior margin of head to tip of acromion 



Posterior margin of head to median (anterior) angle... ,... 



Distance from anterior (coracoid) margin of scapula to tip of acromion 



Distance from tip of coracoid process to median (anterior) angle of scapula. 

 Ma.ximum thickness of scapula at base of acromion 



42.5 

 35.5 

 64.5 



107.2 



155 

 58 



123 

 21 



46 



34 



92 

 115 

 155 



66 

 137.0 



21.5 



> Cat. No. 8842, U. S. Nat. Mus. 



2 Cat. No. 49582, U. S. Nat. Mus. 



HUMERUS 



The humerus is irregularly concave on the internal border, convex 

 on the external, and except for a slight swelling near the lower 

 margin of the lesser tuberosity the outline of the anterior border 

 (pi. 12, fig. 4) is rather evenly concave. The broadly oval head is 

 set off from the shaft by a well-marked neck, which, however, does 

 not extend around upon the proximal surface. The head is large 

 and projects slightly beyond the internal margin. It is barely 

 visible when the humerus is viewed from in front, and when viewed 

 from the side it is seen to lie below the lesser tuberosity, being sepa- 

 rated from it laterally by a narrow groove. The deltoid crest is 

 represented by a low swelling on the external face of the shaft. 

 About halfway between the head and the inner trochlea there is a 

 smaller but more evident protuberance on the angle formed by the 

 internal and posterior faces. On the anterior face of the shaft there 

 are two short elongate depressions that are almost continuous with 

 one another, which commence near the upper margin of the inner 



