BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 21, pp. 249-284, PLS. 6-17 JUNE 15, 1910 



CACOPS, DESMOSPONDYLUS; NEW GENEEA OF PEEMIAN 



VEETEBEATES^ 



•BY S. W. WILLISTON 



{Presented in abstract before the Paleontological Society Dec. 30, 1909) 



CONTENTS 



Page 



Introduction 250 



Character of the Permian beds of northern Texas 250 



Conditions of fossilization 250 



Associated vertebrates 252 



Cacops aspiclephorus — genus and species ne^Y 253 



Skull 253 



Vertebrae 256 



Carapace 258 



Carapace in allied forms 259 



Hypocentra 261 



Pleurocentra 261 



Atlas 262 



Sacrum 263 



Tail 264 



Ribs 265 



Significance of hypocentra and pleurocentra 265 



Pectoral girdle and extremity 268 



Scapula coracoid 268 



Cleithrum 269 



Clavicles 269 



Interclavicle 269 



Humerus 270 



Humeri of allied forms 270 



Radius 274 



Ulna 274 



Pelvic girdle and extremity 274 



Pelvis 274 



Femur 275 



Tibia 276 



Fibula 276 



1 Manuscript received by the Secretary of the Geological Society April 23. 1910. 



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