GILMORE: OSTEOLOGY OF BAPTANODON (MARSH) 113 
plate whose outer apices are produced to form the ends of the transverse bar. This 
transverse portion lies in a groove on the posterior side of the clavicles and when 
in position only the stem could be seen from an inferior view of the girdle. (See 
PL. XIL,, fig. 3.) An examination of fig. 21 shows the interclavicle slightly removed 
to the left from its natural position in the groove of the clavicles. 
The upper posterior side of the stem is gently concave from side to side, indicating 
that it probably underlapped the median ventral sur- 
faces of the coracoids, thus giving support to the for- 
ward part of the arch. 
Nothing is known of the pelvic girdle at this 
time. 
Anterior Limbs.— Professor Marsh briefly described Fic. 22. Inferior view of inter- 
the fore paddle (probably pertaining to specimen No,  ©lavicle of Buptanodon discus (No. 878). 
One fifth natural size. 
1958) of Baptanodon as follows: “In the fore paddle 
the humerus alone is differentiated. Below this the bones of the forearm, the car- 
pals, metacarpals and phalanges are essentially rounded free disks implanted in the 
primitive cartilage. The radius may perhaps be regarded as a partial exception, as 
its free margin is nearly straight and somewhat thinner than the remaining border. 
There are three bones of nearly equal size in the first row below the humerus. The 
radius may be identified with certainty by its position. The next bone evidently 
corresponds to the intermedium * and the third or outer one, to the ulna. In the 
succeeding row there are four subcircular bones, and five in the next series. These 
represent the carpals. ‘There are six metacarpals, and also six well-developed digits, 
each composed of numerous phalanges, which are free and nearly circular in form.” 
Knight has given additional information of the paddle bones in the following 
lines: “The carpals, metacarpals and phalanges are compressed grooved cylinders 
the most of which have slightly concave surfaces. The grooves are ornamented with 
tuberosities for musular attachment. Along the margins of the limb the cylinders 
have their exterior borders reduced to quite thin edges. Anyone finding the limb 
of a Baptanodon for the first time scattered about in the field would surely try to fit 
the ventral and dorsal surfaces of the metacarpals in trying to construct a digit.” 
There is nothing to be added to this description by our material which consists 
of the proximal end of a humerus (see fig. 21, h), and a few miscellaneous paddle 
bones. 
Humerus (h.). — Knight describes the humerus of B. marshi briefly as follows: 
44 Now considered the ulna, while the succeeding element is identified as the pisiform. Dr. Williston proposes 
the name ‘‘ epipodial supernumerary ’’ for the latter. 
