PLATE XXII. 
PERMIAN VERTEBRATES. SKELETON OF DIMETRODON 
Fics. 1-11. Dimetrodon incisivus Cope. Parts of skull and vertebrae, two-fifths natural size 
(except figs, 8-9). Amer. Mus. No. 4008, Cope Coll. Lower Permian, North 
Fork of Little Wichita River, Texas. 
Fig. 1, la. Front of skull, with fragment of lower jaw attached, fig. 2, 2a, 2b, 
quadrate; figs. 3-5, vertebral column, axis to second caudal complete, spines mostly 
broken off; figs. 6, 7, anterior and posterior views of anterior dorsal vertebra 
(14th of this series); figs. 8, 9, posterior view of posterior dorsal and anterior 
view of sacral vertebra, both natural size; figs. 10, 10a, caudal vertebre; fig. 11, 
mass of vertebral spines with head of rib attached. 
