A DESCRIPTION OF THE GENUS DIMETRODON, COPE. 



23 



" In a medium-sized specimen of Dimetrodon incisivus, where the vertebral body is 

 35 mm. in length, the elevation of the neural spine is 900 mm., or twenty and a half 

 times as great." The interclavicle is described as sternum and figured PL III, Fig. 5. 

 A posterior foot of Theropleura (spec. ?) is figured and described. 



Naosaurus differs from Dimetrodon in the presence of transverse processes on the 

 neural spines. Portions of the skull and vertebrae of Naosaurus claviger are described 

 and figured (PL II, Figs. 1-3 ; PL III, Fig. 1). Vertebrae of Naosaurus cruciger and 

 N microdus are also figured (PL III, Figs. 2 and 3). 



In 1887 Baur 21 > 22 > 23 gave the following diagram to express the relationship between 

 the Theromorpha, the other Reptiles and the Mammals : 



RHYNCHOCEPHALIA 



'V 



PflOGANOSAUHIA 



Lydekker in 1890 24 describes some Pelycosaurian remains from the Permian of Texas 

 in his " Catalogue of the Fossil Reptiliaand Amphibia in the British Museum," Part IV. 

 1. Pieces of the maxilla and neural spines of Naosaurus cruciger Cope. 2. Portions of 

 spines of Naosaurus claviger Cope, and of undetermined species of Naosaurus. 3. Two 

 dorsal vertebrae and an intervening intercentrum of Embolophorus spec. 4. Two dorsal 



