1 50 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



tebrae which are very similar in form to those exhibited by the type of the species. 

 To the vertebrae are articulated short, curved ribs of a slender nature. The ver- 

 tebrae themselves are short and somewhat constricted in the middle. 



The other impression, 8699 G, contains impressions of about 20 vertebrae, appar- 

 ently immature, though one can not be entirely sure as to the nature of the struc- 

 tures. They are covered over with a thin layer of carbonaceous material which is 

 impossible to remove satisfactorily. The two specimens remind one of what Hux- 

 ley has written in regard to the forms of Microsauria (334) from Kilkenny, Ireland. 



MEASUREMENTS OF Nos. 7 AND 8699 G (MOLGOPHIS WHEATLEYI). 



mm. 



Length of No. 7 87 Length of vertebra 2 



Length of head mold 18 Length of rib 3 



Posterior width of head 6 Length of specimen No. 8699 G 53 



Genus ERPETOBRACHIUM Moodie, 1912. 

 MOODIE, Kans. Univ. Sci. Bull., vi, No. 2, p. 3,53, 1912. 



Type: Erpetobrachium mazonensis Moodie. 



The generic characters are apparent in the greatly elongated fore limb, in the 

 exceptionally broad scapula, the long radius and ulna, which slightly exceed the 

 humerus in length, a character hitherto unknown among Carboniferous Amphibia. 



Erpetobrachium mazonensis Moodie. 

 MOODIE, Kans. Univ. Sci. Bull., vi, No. 2, pp. 353-354, pi. 2, fig. 2; pi. 8, fig. 3, 1912. 



Type: Specimen No. 799 (222), Yale University Museum. 



Horizon and locality : Mazon Creek shales, near Morris, Illinois. 



The scapula of the present form is exceptional in its shape. It resembles an 

 asymmetrical pyramid, the anterior side of the lower edge of the bone being con- 

 tracted so that the anterior edge of the element is arcuate. Its top is very thin and 

 possibly terminated in a broad cartilage. The lower end is thick and heavy and 

 the articular surface is, apparently, well formed, though somewhat obscured. 



The element identified as a clavicle is lying on its edge and has the proportions 

 of the clavicle of Mazonerpeton costatum. The exterior edge is somewhat rounded 

 and small. A portion of another element which I suppose to represent the coracoid 

 lies alongside the humerus, although its form is quite obscured. (Plate 3, fig. 3.) 



The humerus has a remarkably well-formed head. In perfection of formation 

 it corresponds well with that of the higher reptiles. This surface can even be divided 

 into an anterior and a posterior articulation. The element projects posteriorly for 

 the distance of I mm. from the surface of the shaft. The shaft immediately below 

 the head is somewhat flattened and has an ovoid section. Further on it becomes 

 flattened, a part of which is probably due to pressure during fossilization. 



The elements of the forearm are both preserved and are approximately equal in 

 size. They are remarkable in that they exceed the humerus in length, although 

 they are not so heavy as that element. They are greatly elongate and slender, with 

 the middle of the shaft only moderately contracted. The articular surfaces are 

 well formed and both bones were hollow, as was also, apparently, the humerus. 

 The ulna may be represented by the most posterior of the two elements, though 

 the relations of the elements may have been reversed (fig. 15, D). 



