No. 2300. SKELETON OF DIMETRODON GIGAS—GILMORE 539 



The proximal row of phalanges, except on digit 1, have widely ex- 

 panded proximal ends and much narrower distal extremities. The 

 distal articulation is peculiar in having a blunt median projection 

 which is received in a median notch provided for it on the proximal 

 ends of the succeeding phalanges. The toes are terminated by 

 strong, clawed terminal phalanges that were cased in strong claws. 

 The whole structure of the carpus and other bones indicates a strong, 

 flexible foot, such as would be possessed by a carnivorous terrestrial 

 animal. 



EXPLANATION OF PLATES. 



Plate 70. 



Mounted skeleton of Dimetrodon gigas Cope. No. 8635, U.S.N.M. Viewed from 

 the left side. About one-twelfth natural size. Mounted by Thomas J. Home, 

 1918. 



Plate 71. 



Skeleton of Divietrodon gigas Cope. No. 8635, U.S.N.M. About one-twelfth natiiral 

 size. Those parts shown in outline are missing. The sacrum of three vertebrae, 

 pelvis, and interclavicle bones have been introduced from other individuals. 



Plate 72. 



Fig. 1. Mounted skeleton of Dimetrodon gigas Cope. No. 8635, U.S.N.M. Viewed 

 from the rear in order to show the shape of the body cavity and the pose of the 

 fore limbs. 



Fig. 2. Mounted skeleton of Dimetrodon gigas Cope. No. 8635, U.S.N.M. Viewed 

 diagonally from the left side, in order to show the articulated pectoral girdle. 



Plate 73. 



Model restoration of Dimetrodon gigas based on the mounted skeleton shown in plates 

 70 and 72. About one-twelfth natural size. Modeled by Charles W. Gihnore, 1918. 

 Inset is Basiliscus plumifrons a living lizard, found in Central America, which has 

 a fin-like extension of the neural processes as in Dimetrodon. About one-third 

 natural size. After Cope. 



