Apr. 1903. Norru AMERICAN PLESIOSAURS—WILLISTON. a 
carpal; distally with the fourth metacarpal, and internally with the 
fourth distal carpal by two facets, leaving an emargination between 
them, which, with the opposing surface, formsaforamen. The fourth 
bone of this row is, I believe, in reality the fifth metacarpal, which 
has receded proximally to articulate with the first 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. JDaistally 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 meta- 
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, emarginated 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 
are 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 the free borders, while those of the intervening fingers 
have the sides more or less flattened, with a greater thickness dorso- 
ventrally 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. 
