152 



THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



Ulna 



Parts of two individuals express the typical characters of this species, while a 

 third only differs in being considerably smaller. A fourth may very probably be 

 referred here, and another, bearing several elements of a leg, should be most likely 

 associated with the last mentioned. 



The ribs are considerably narrowed near the head, and appear to possess a low 

 tubercular process some distance below it. The shaft is curved 

 throughout; the laminar expansion is quite thin; while the distal 

 end is expanded and concave, perhaps for the attachment of car- 

 tilage, although no trace of this remains on the shale. The neural 

 spines have short bases, oblique anterior and nearly straight pos- 

 terior borders, with obtuse extremity. I perceive no essential dif- 

 ference in the smaller specimen, which is one-third less than the 

 types. 



The limb is appropriate in its proportions to the present 

 species, and may be described in this place. The first segment 

 is one-third longer than the second, and has a transversely 

 expanded head. The shaft is stout, the distal extremity not 

 expanded and concave. The second segment is stout, more ex- 

 panded proximally than distally, the proximal end truncate and 

 slightly concave. A bone, much displaced, lies near it, and is p IG . 33 ._Foreiimbof a 

 probably ulna or radius; it is as stout as the first, the end not member of theMoi- 



gophicia?, possibly 



expanded. Of metatarsals there are 2, three-fifths the length Pieuroptyx clavatus 

 of the second bone of the leg, and of phalanges 2, of 2 digits 

 each. The proximal are three-fourths the length of the metatarsals, and indicate 

 elongate toes. The obverse of the specimen is preserved, and contains no addi- 

 tional toes or phalanges. 



MEASUREMENTS OF THE TYPE OF PLEUROPTYX CLAVATUS COPE. 



Phalanges, 



Length of vertebral centrum 14 



Depth of a vertebral centrum 9 



Depth of entire vertebra 22 



Length of neural spine 8 



Height of a neural spine 6 



Length of a rib on the curve. 42 



Width of a rib at ala 9 



Width of a rib at extremity 5 



Length of first segment of leg 38 



Length of second segment of leg. . . 24 



Length of metapodial bone 10 



Length of first phalanx 7 



Hitherto only two portions of the dorsal series and a left limb have been assigned 

 to this species. The present specimen (No. 4479, U. S. Nat. Mus.) thus proves of 

 interest in determining that the creature was long-tailed, like CEstocephaliis, Ptyo- 

 n ins, and Phlegethontia, but unlike the first two genera the neural and haemal spines 

 are not elongate nor marked with radiating lines. The neural spines are indistinct 

 and if developed at all were very low and short. 



The centra are short, cylindrical, and thick. They gradually decrease in size 

 to where they are lost, since the portion preserved does not represent the entire 

 length of the tail. There may have been 15 more vertebras distally and 5 more 

 proximally, thus making about 75 caudal vertebrae, as Woodward (630) has deter- 

 mined obtains in Ccratcrpeton galvnni Huxley. 



