184 A NEW FOSSIL PORPOISE FROM MARYLAND. 



Phocama in that the coracoid and acromion are both directed downward; but, 

 as will be shown below, this resemblance is probably illusive. The inferior 

 border of the coracoid is nearly straight and descends from the border of the 

 glenoid fossa. The process itself is oblong and scarcely at all expanded at the 

 extremity. The acromion is similar in shape and of about the same length, but 

 the extremity is rounded off. While this is its present form, it is evident, upon 

 close examination, that the superior border is defective. There is a probability, 

 therefore, that it had an ascending distal portion originally, as in Sotalia and 

 many other recent delphinoids. 



The posterior border of the scapula is deeply concave, and the superior 

 border quite strongly and evenly convex with a perceptible dip anteriorly, while 

 the anterior border is evenly, but not strongly, concave. The even convexity 

 of the superior border is doubtless partly due to immaturity. The internal 

 surface of the scapula shows scarcely any trace of ridges and depressions, while 

 the external surface is hidden in the matrix. 



The dimensions of the scapula are as follows: Length of superior border, 

 163 mm.; height above glenoid fossa, 103; length of acromion (imperfect), 34; 

 length of coracoid process, 28. 



Pectoral Limb. 



The bones of the pectoral limb, as a whole, are quite unlike those of typical 

 recent delphinoids, and remind one rather of Inia, Eurhinodelphis, and Berardius, 



though differing from any of these. 



Humerus (PL XXV, fig. 2) .—The humerus is as long as the radius. It is irregu- 

 larly concave on the upper (or posterior) border, and irregularly convex on the 

 lower (or anterior) border, and the outline of the internal face is strongly concave. 

 The head is large and placed obliquely. The greater tubercle is scarcely visible 

 over the condyle when the humerus is viewed from in front, but when viewed 

 from the side it is seen that it is a very little higher than the condyle. The 

 bicipital groove is broad and very shallow. The deltoid ridge is but little salient 

 being represented rather by a large, low, elliptical swelling on the border of the 

 shaft. There is a similar, but smaller and more angular protuberance on the 

 upper (or posterior) border of the shaft. The external surface is marked by a 

 deep pit, situated nearer the proximal than the distal end. The articular facets 

 for the radius and ulna are very distinct, but form only a slight angle with one 

 another. The ulnar facet extends some distance up the upper border of the ulna. 



Radius (PL XXV, fig. 3) .—The radius is strongly curved, rather flat, and a little 

 more expanded and thinner at the distal end than at the proximal end. 

 lower (or anterior) border is strongly convex, and the upper (or posterior) bor e , 

 strongly concave. It follows from this, and the fact that the ulna has cum 

 margins, that there is a large elliptical vacant space between the two bones, w 



> 



ordinary recent delphinoids are in contact. 

 Ulna (PL XXV, fig. 4).— The ulna is more slender than the radius 



It 



straight, but greatly expanded distally and somewhat so proximally, w i 





