Apr. 1903. North American Plbsjosaurs Willistok. 71 



carpal: distally with the fourth metacarpal, and internally with the 

 fourth distal carpal by two facets, leaving an emargination between 

 tlum, which, with the opposing surface, forms a foramen. The fourth 

 hone of this row is, I believe, in reality the fifth metacarpal, which 

 has receded proximally to articulate with the hist row: with this inter- 

 pretation there may have been some displacement of the carpals 

 proximally. The bone is elongate, phalange-shaped, articulating 

 proximally with the ulnare, externally by two facets, having an 

 emargination between them, with the third distal carpal. Distally it 

 articulates with a phalange, and on the outer angle with the fourth 

 metacarpal. 



The metacarpals are shorter than the first phalanges of their 

 respective fingers. The first is nearly square, articulating with the 

 first distal carpal, the second metacarpal and its phalange; the outer 

 border is similar to that of the first distal carpal. The second nn ta- 

 carpal is a peculiar bone, easily recognizable in isolated examples: it 

 joins the first metacarpal externally, the phalange distally, the third 

 metacarpal internally by articular surfaces, emar^inated between 

 them, and proximally by two unequal facets, the first and second 

 distal carpals. The third metacarpal is also closely wedged in 

 between the second and third metacarpals, the phalange and second 

 distal carpal. The fourth metacarpal is scarcely distinguishable from 

 a phalange; while the fifth of the row seems to be a phalange. 



Of the phalanges only those of the first and fifth fingers are cer- 

 tainly placed in the figured paddle : the others must have been, in 

 the living animal, very nearly as they are here figured, but the 

 absence of distinct lateral articular facets renders the assumed loca- 

 tions uncertain. The proximal ends of the outer four of the first row 

 arc in nearly the same straight line, but those of the inner fingers 

 become successively less and less elongate, giving an increased 

 'obliquity of the articulations, and more and more definite interlock- 

 ing of the bones. Those of the first and fifth digits are more or less 

 thinned on tin free borders, while those of the intervening fingers 

 have tin sides more or less flattened, with a greater thickness dorso- 

 \ eiitrally than from side to side. The distal bones, however, become 

 more and more flattened from above. They are all gently hour-glass 

 shaped. There are at least ten phalanges in the first finger, fifteen 

 in the second, and perhaps as many as twenty in some of the others. 



