EXTINCT AMPHIBIA OF NORTH AMERICA 59 
the scapulae are shifted as far backward. ‘There can be little 
doubt however that the pectoral arch was not far removed from the 
cranium. There is an oval fragment preserved on the left of the 
specimen which I take to be a portion of the coracoid. ‘The scapula is 
preserved entire on the left side and it is represented by fragments on 
the right side. It is almost semicircular in form and narrows exter- 
nally until it is somewhat fan-shaped. There appears to be an 
ornamentation of lines on the surface of the bone. ‘These lines follow 
the contour of the anterior border. 
The forearm is represented nearly complete on the left side and the 
right side shows the humerus and the forearm. The humeri are 
unusual in that they have well-developed articular ends as though 
the development of the endochondral tissue was well developed in the 
form. The humerus is expanded at the ends and it is larger at the 
upper than at the lower end. The ulna is expanded at the proximal 
but is more attenuated at the distal portion. It is shorter than the 
humerus by about one-third of its own length. The radius is a mere 
slender rod of bone and presents the well-developed articular ends. 
It is slightly shorter than the ulna. .The carpus is unossified and its 
position is represented by a blank space. There are phalanges of 
four digits preserved and this, apparently, represents the entire number 
of digits. There is one digit, the second, which has all of the phalanges 
preserved and they are four in number. The phalangeal elements 
like the other bones of the extremity have the articular surfaces. 
prominent. The terminal phalanx is claw-like. 
There are no ribs nor traces of them preserved and a conjecture as 
to their character cannot be hazarded since they are known in but two 
other species, in which they are curved. There is no evidence of a 
ventral scutellation and so far as is at present known this structure is 
absent from all of the species of the genus or at least it is but weakly 
developed. It is not present in the well-preserved 7. scaulptilis 
described below. 
Of the pelvis the ilium alone is represented. The bone itself has 
disappeared and has left a depression which shows this element to have 
been an elongate rod very similar to that described for Mzcrerpeton. 
The sacral vertebra seems to be indicated by a depression between 
the iliac depressions. 
