74 AMERICAN PERMIAN VERTEBRATES 



That it belongs with the femora seems probable because, not only 

 agreeing in size, it shows the same lack of articular ossification so 

 characteristic of this genus. The bone is much curved; the 

 shaft slender; the upper extremity much expanded. The outer 

 border is very deeply concave, as is also the posterior. The upper 

 end is gently convex, with angular margins; it is elongate, with a 

 small anterior projection. The lower, sharply truncate end is 

 obliquely ovate in shape; the posterior inner part narrower. 



A smaller tibia, about three-fifths the length of the larger one, 

 agrees in general characters, save that the cnemial convexity is 

 less pronounced. It probably belongs with femora referred to 

 Clepsydrops. 



The fibula shown in Plate XXX, Fig. n, in much probability 

 belongs with Clepsydrops, but this is not at all certain. The 

 shaft is only moderately slender; the lower end is much dilated, 

 and the articular surface is not at all oblique to the long axis of 

 the bone, as in the same plate, Fig. 9. Various carpal and tarsal 

 bones preserved evidently belong with this genus, and especially 

 the astragalus shown in plate XXXII, Fig. 9, and the calcaneum 

 shown in Plate XXXI, Fig. 10, and Plate XXXII, Fig. n. 



Humerus (Plate XXXI, Fig. 3). — There are several humeri 

 which agree well with those referred to C. natalis by Case and Cope, 

 and doubtless of the same species as one or the other of the large 

 femora figured in Plate XXX. Like the femora, the extremities 

 were largely cartilaginous in life, the condyles undeveloped. The 

 lateral process reaches about one-third the length of the bone; 

 the plane of the inner side above is at about sixty degrees with 

 that of the lower end. The entepicondylar foramen is large, and 

 is remote from the border. The upper angles of the cartilaginous 

 borders of the condyles are nearly opposite each other, and are 

 low down, the two sides of the bone nearly symmetrical below the 

 lateral process. 



With the half-dozen large humeri there are as many more of 

 small size, a half or less the length of the larger, which doubtless 

 are of young animals; one is shown in Plate XXX, Fig. 5. They 

 agree in general with the larger ones, except that the shaft is more 

 slender and the ends less well ossified, the lateral process is rela- 



