SYSTEMATIC REVISION OF THE SUBORDER. 51 



Measure}nenls. 



m. m. 



Length of the dental series 0.252 Diameters of third maxillary at alveolar border: 



premaxillary series (and bone) .049 Antero-posterior 0.020 



diastema 024 Transverse 005 



first premaxillary tooth from alveo- Diameters of third maxillary at base of crown: 



lar border 057 Antero-posterior .018 



Diameters of first premaxillary tooth at alveolar Transverse 015 



border: Length of seventh maxillary from alveolus 026 



Antero-posterior 022 Diameters of crown at base of cutting edge: 



Transverse .015 Antero-posterior 012 



Length of third maxillary from alveolar border .067 Transverse 009 



" The approximation to a two-rooted condition in some of the teeth is a marked 

 peculiarity of this species. The median groove is most extensive on the smaller max- 

 illary tooth, extending into the base of the crown." 



The figure 00 -shaped roots of the teeth described as characteristic of tlie 

 species occur in only two of the nearly complete series of teeth. An exam- 

 ination of the broken surface of the root of the large canine with a hand lens 

 shows that the walls have been broken and crushed in to take the figure 00 - 

 shape. In the natural condition the root had only a slight depression on 

 either side, giving it a semiquadrangular outline. 



The described excavation of the nasal bones by the nostril is an error, 

 the part considered by Cope as the end of the nasal in Dimetrodon incisivtis 

 being the septo-maxillary . This has fallen out in Dimetrodon sentiradicatus. 



The shape of the root of the incisor teeth in the premaxillary would be 

 different if taken at any other place ; the base of the root is semiquadran- 

 gular as in Dimetrodon incisivus. 



This is a synonym of Dimetrodon incisivus. 



Dimetrodon dollOYianus Cope. 



Embolofhorus doUovianus Cope. 



Cope, Proc. Am. Phil. Soc, vol. xii, 1884, p. 43, plate i, figs. 4, 4a, and 4b. 

 Cope, Proc. Am. Assn. Adv. So. Phila., 1884, p. 471. (Same plate as preceding.) 

 Case, Jnl. Geol., vol. xvr, 1903, p. i. 32 figs. 



Type : A collection of fragments of a skeleton including parts of the skull, the 

 neural arch of the atlas, third and fourth cervicals, fragments of dorsals, an imperfect 

 sacrum, and astragalus. The third cervical with its attached intercentrum was 

 described as having the typical characters. No. 4064 Am. Mus. Nat. Hist., Cope, 

 coll.; from the Indian Territory. 



Homeotype : A skull, nearly complete vertebral column, shoulder girdle, pelvis, 

 and fragments of limb bones. No. 114 University of Chicago. From Coffee creek, 

 a tributary of the Big Wichita river in Vernon county, Texas. 



Original description : In 1884 Cope read two papers (60, 66) in which an 

 identical plate bore a figure labeled, a dorsal of a species of Embolophorus. 

 In one of these papers (60) appears the following description of this vertebra : 



"The articulation of the ribs in Embolophorus. — The ribs of the Theromorpha 

 are two-headed. While the tubercular articulation has the usual position at the ex- 

 tremity of the diapophysis, the capitular is not distinctly, or is but partially indicated, 

 on the anterior edge of the centrum, in Clepsy drops and Dimetrodon. InEmbolophoruSy 



