50 



PROCEEDINGS OF THE NATIONAL MUSEUM 

 Measurements of the chevron bones {in millimeters) 



VOL. CO 



Depth of chevron 



Aiitero-posterior diameter of blade at ex- 

 tremity 



Antero-posterior diameter of articular 

 facet on base of chevron (right side) 



Distance between internal margins of ar- 

 ticular facets on base of chevron 



Chevron 

 No. 4, pi. 

 11, fig. 8 



7.7 

 16. 2 

 11 



5 



SCAPULA 



The anterior half of the left scapula (pi. 1, fig. 1) is missing, 

 but the posterior half is complete. The internal face is exposed and 

 the external is hidden in the matrix. Aside from its smaller size, 

 it resembles the corresponding portion of the scapula of Delphinodon 

 dividum, but the posterior margin is not as deeply concave. The 

 vertebral border is evenly convex. Scarcely any trace of ridges 

 can be observed on the internal face of the blade, but there is a shallow 

 dejjression in the mesial region which corresponds in a general way 

 to the insertion of the subscapulars muscle. Between this depression 

 and the posterior angle the internal surface of the scapula is flat; 

 the serratus anticus muscle is inserted in this region in living por- 

 poises. 



Measurements of the left scapula (in millimeters) 



Exterointerual diameter of head 16 



Posterior margin of head to posterior angle of blade 78 



Inferior margin of head of vertebral margin of blade 86 



HUMERUS 



With the exception of a portion of the epiphysis from the prox- 

 imal end, all of the right humerus is missing. In size, this humerus 

 is smaller than any of those hitherto obtained from the Calvert 

 formation. The lesser tuberosity is considerably larger than the 

 greater tuberosity, an anomalous condition which prevails in many 

 of the living porpoises. On the outer half of the proximal face of 

 the lesser tuberosity there is a well-defined ovoidal concavity which 

 corresponds in position to the usual place for the attachment of the 

 subdeltoid muscle. The bicipital groove is deep. The external face 

 of the greater tuberosity is very rugose and in this area was attached 

 a part of the deltoid muscle. Most of the head is missing. 



