134 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



the low neural ridge, which takes the form observed in Thyrsidium, Molgophis, Phleg- 

 ethontia, Dolichosoma (fig. 8) and other genera. The vertebrae are strongly amphi- 

 ccelous and the notochord was probably persistent. The sides of the vertebrae are 

 smooth. 



The ribs are all intercentral in position; the anterior ones very broad near the 

 base, recalling the broadly expanded ribs described by Schwarz (540) for Scincosau- 

 rits, Ptyoniiis, Thyrsidium, and other genera. Posteriorly the ribs become slender 

 and cylindrical. They are all rather long and distinctly curved, with probably a 

 cartilaginous tip. 



There is preserved a single element of the right side of the pectoral girdle. This 

 is, I think, the coracoid, an element which has hitherto escaped observation among 

 the American Microsauria. It is long and spatulate at both ends, with the median 

 portion apparently almost cylindrical, not unlike that described by Credner (181) 

 for the coracoid of Branchiosaurus, save that the lower end of the branchiosaurian 

 coracoid is acuminate. In the present form it is spatulate. Its relations with the 

 other elements of the pectoral girdle have never been satisfactorily determined. 



The fore limbs are both partially preserved. The humerus of the right side is 

 complete. It is greatly elongated for a microsaurian. The form of the element is 

 not unlike that of a lizard, with the lower end of the bone spatulate and endochon- 

 drium well developed. Very little difference can be seen between the form of the 

 arm bones, which represent the radius and ulna. They are both elongated, with con- 

 stricted median portion and expanded truncate ends. The carpus is unossified and 

 the cartilage has left no trace of the elements. 



The right hand has two metacarpals preserved, which are fvilly half as long as 

 the radius and ulna. They are separated some little distance from the ends of these 

 elements, though this may be due to post-mortem shifting. The carpus may, how- 

 ever, have been broad. On the left side are preserved portions of the humerus, 

 radius, vilna, and 3 metacarpals, lying close to the vertebral column. The carpal 

 space is not so large on the left as on the right. The ventral armature is well 

 preserved in a narrow patch about an inch in length. The chevron-shaped rods 

 are quite large, there being 2 of them in i mm. 



Measurements. 



nun. mm. 



Entire length of fossil 98 Median width of a centrum 1.5 



Length of skull 22 Length of rib 6.5 



Width across base of skull 28 Width of rib at base 33 



Long diameter of eye 10.5 Length of coracoid 8 



Transverse diameter of eye 8 Width of coracoid at anterior end 2.5 



Interorbital space 4 Length of carpal space 5 



Length of mandible 26 Length of humerus 18 



Depth of mandible at coronoidal region 3.5 Width of shaft I 



Depth of dentary 2 Distal width of humerus 4 



Length of long tooth 2 Length of radius and ulna 10.5 



Diameter of long tooth at base .5 Length of metacarpal 6 



Length of preserved portion of vertebral column ... 64 Length of ventral armature preserved 34 



Length of a centrum 3 Number of rods in length of 5 mm 10 



