246 KANSAS UNIVERSITY SCIENCE BULLETIN. 



lines like the spokes of a wheel, pursue a tortuous course as 

 they run from the central small pulp chamber toward the sur- 

 face. Not only do they undulate, but they give off lateral proc- 

 esses, and at their terminations near the surface of the tooth 

 the thin laminae of pulp (so thin that the radiating pulp cham- 

 bers are mere fissures) become dilated; so that on section cir- 

 cular canals are seen at these points, as is also the case at the 

 points where subsidiary processes branch off." (Dental An- 

 atomy, 5th edition, 1898, p. 65.) 



Measurements of the mandible of Eryops willistoni: 



Greatest length 48 cm. 



Length of posterior portion (fig. 1) 33 



Greatest width 10 



Width of dentary midway from coronoid process 6.5 



Width across articular 2.6 



Length of tooth 2 , 



Thickness of same at base 5 



The right arm of this species is preserved in an incomplete 

 condition, as may be seen by reference to plate LII. The form, 

 of the humerus is well shown in the figures, plate LIII, fig. 7, 

 and plate LII. It suggests to a certain extent the humerus of 

 a mosasaur. The present element does not have the bizarre 

 appearance which exists with the specimen of that element of 

 Eryops megacephalus figured by Professor Cope in 1890 

 (Trans. Amer. Philos. Soc, vol. XVI, p. 367, fig. 3). The large 

 projections are wanting entirely from one side and on the other 

 they are not so highly developed, and yet the form of the bone 

 is such that it can be nothing else save a humerus. It is too 

 rugged for a femur. 



The specimen is abraded to some extent, so that the exact 

 form of the element cannot be determined. It may have had 

 the form suggested by the broken lines in the figures. The 

 humerus is that of the right side. Viewed from in front the 

 element is seen to have a peculiar form (plate LIII, fig. 7). 

 The lower portion of the inner surface is distinctly concave. 

 The inner side of the bone is comparatively smooth. There is 

 a low ridge which runs obliquely across the antero-superior 

 angle of the bone. There is a distinct twist in the inner sur- 

 face, which is continued to such an extent that the inner sur- 

 face is carried around almost parallel with a portion of the 

 outer surface. It then takes another and inward curve and 

 ends in a projection. 



One of the projections from the outer surface of the humerus 



