SCOTT : LITOPTERNA OF THE SANTA CRUZ BEDS. 1 35 



mar side it is extremely prominent and sharp. It is strengthened, as in 

 the other metacarpals, by extending up the palmar side of the shaft into 

 a non-articular ridge. 



Metacarpal IV is the counterpart of mc. II, though slightly shorter, not 

 rising so high into the carpus proximally and extending distally a little 

 below the end of mc. II. The head bears a prominent palmar ridge-like 

 process, which, however, is less massive than that of mc. Ill ; the unci- 

 form facet is convex and slightly oblique, broad dorsally and narrowing 

 much toward the palmar side. On the radial side of the head are two 

 surfaces for mc. Ill, that on the dorsal side prominent and convex, that 

 on the palmar side sessile and plane, and on the ulnar side is a small 

 facet for the minute mc. V. The shaft and trochlea resemble those of 

 mc. II reversed. 



The vestigial fifth metacarpal has not been found, but its presence may 

 be confidently inferred from the facets on the unciform and mc. IV. 



The phalanges of the first row are long and slender and are much alike 

 in all three digits, except that in the median digit this phalanx is shorter 

 than in the laterals, a very unusual proportion in a foot of mesaxonic 

 symmetry, as well as broader and more depressed. In all the phalanges 

 of this row the proximal trochlea is a shallow concavity, deeply divided 

 by the groove for the metacarpal carina. The distal trochlea is simply 

 saddle-shaped, but with the articular surface reflected far over upon the 

 dorsal side. 



In the second row the phalanges are short, broad and heavy, with thick 

 proximal and much depressed distal ends. In the median line the dorsal 

 lip of the proximal trochlea is produced into a more or less prominent, 

 beak-like process. The second phalanges of all the digits are of nearly 

 equal length ; in the third digit it is slightly longer than in the second or 

 fourth. 



The ungual phalanges are short, broad, thick and almost nodular in 

 shape, resembling somewhat those of the slender-footed Oligocene rhino- 

 ceroses, but they have lost all vestige of the median cleft. In digit III the 

 ungual is larger than in the laterals, broad and symmetrical, with rugose 

 free border, while those of digits II and IV are quite irregular and 

 asymmetrical. 



The pelvis (PI. XIX, fig. 7) is short and broad and resembles that of 

 Macratichenia, but is less specialized in several particulars. The ilium 



