PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. 



21 



the bones from the two sides. The posterior end of the bone was broad and thin 

 and evidently appHed to the outer face of the posterior end of the scapula. Anteri- 

 orly it contracted to a narrow, relatively short process, which was applied to the 

 upper surface of the scapula or the distal end of the clavicle. 



The humerus: The bone of the right side is perfect, but that of the left side 

 has lost a small fragment from the upper border of the entepicondylar foramen. 

 In general the form is the same as in Diadectes phaseolintis, but differs in some 

 particulars. The proximal and distal ends have about the same inclination to 

 each other as in D. phaseolintis and there is the same lack of any well-defined shaft. 

 The articular face for the scapula is narrow and extends nearly parallel to the 

 greatest length of the head of the humerus instead of obliquely across it, as in the 

 pelycosaurs and some Cotylosauria. Near the inner end of this face is a deep, 

 rather elongate pit, with a prominent lower border but open on the upper edge. 

 Beyond this pit the end of the bone falls away sharply to the inner, deltoid, pro- 



FlG. 10. Diasparactus zenos Case, X ^. A, anterior surface of left humerus; 

 B, posterior view of left humerus; C, view of inner side of left humerus. 



cess, which extends almost directly outward and does not curve downward and 

 inward toward the anterior face of the bone, and does not send an extension down- 

 ward on the shaft, as in the pelycosaurs, nor even so much as in D. phaseolinus. 

 On the extremity of this process is a well-marked pit for the attachment of a strong 

 ligament. The process on the posterior side of the proximal end is fully as promi- 

 nent as that on the anterior end. 



In D. phaseolinus there is a strong process on the anterior, radial, edge of 

 the shaft near its lower end, which extends almost directly outward, probably for 

 the attachment of the supinator muscle; a similar process occurs in the same 

 position in Seymouria, Limnoscelis, though small, and in Sphenacodon and Dimeiro- 

 don, and has been called the ectepicondylar process. In the amphibians Eryops 

 megacephalus, Tretnatops, etc., there is a like process. In this genus there is 

 no such process; the shaft of the left humerus is perfectly smooth at the position 

 of the process, but on the right humerus there is a slightly elevated rugosity. 

 In D. phaseolinus the distal end is relatively broader, the entocondylar process 



