I30 



THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



plete phalangeal formula for the hand of Amphibamus is unknown. The third 

 digit seems to have 4 elements. The formula 2-2-3-2 has been suggested (462). 



The pelvis is very satisfactorily known. The ilium is a long, slender, straight 

 rod, with expanded ends. The ischium is shown on both sides of the vertebral 

 column in the Yale specimen. Its form is almost identical with that of Paleohatleria 

 longicaudata Credner, from the Rothliegenden of Saxony. The ischia are apparently 

 approximate in the median line, though this character is somewhat obscured by the 

 impression of the caudal vertebra;. Their relation with the ilium, other than that 

 they were posterior to it, is uncertain. The pubis is, apparently, calcified cartilage. 

 It is a squarish plate, somewhat corrugated, lying anterior to the ilium in the Dan- 

 iels specimen. The elements of the pelvis were vmdoubtedly hung loosely in the 

 flesh, as in modem salamanders, since there is no indication of articular surfaces. 



The hind limb is well known, the type having a nearly complete leg with the 

 foot. The Daniels and the Yale specimens supplement and substantiate the type. 

 The femur is longer than the humerus, but more slender, with its articular surfaces 



Fig. 28. ^Restoration of probable appearance of Amphibamus grandiceps Cope on the 

 basis of the material described herewith. X 1.5. 



about as well developed as in the humerus. The element is a simple rod of bone 

 without muscular crests of any kind. The tibia and fibula are, likewise, slender 

 separate rods of bone. The tarsus is unossified. The phalangeal formula is 2-2-3- 

 4-3, and is fairly definite. 



In the type specimen the matrix in the orbit was blackened as if by the pigtnen- 

 tutn nigrum of the choroid. The same has been noticed in other specimens. Pro- 

 fessor Cope thought this indicated that the animal was nocturnal. 



There are many characters in Amphibamus which seem to approximate the rep- 

 tilian type of structure. Among these may be mentioned the character of the artic- 

 ular surfaces of the limb bones, the intercentral position of the ribs, the incipient 

 double-headedness and the curvature of the ribs, the presence of a cartilaginous 

 calcified pubis, the length of the limbs, and the clawed character of the phalanges. 



Amphibamus was a low, flat, short, and undoubtedly a creeping, crawling ani- 

 mal, possibly spending a portion of its time in the water; but it could not have been 

 a swimmer. It was one of nattu"e's first attempts at constructing a land vertebrate. 



