SYSTEMATIC REVISION 79 



FOREIGN FORM. 



Genus DIPLOVERTEBRON Fritsch. 



Diplovertebron punctatum Fritsch. 



Fauna der Gaskohle u. der Kalksteine des Permformation Bonmens, vol. ii. 



Type: A few caudal vertebrae and fragments of limb bones. From the 

 Gaskohle o Nyran. 



This genus certainly belongs to the Embolomerus division and prob- 

 ably to the family Cricotides, but is so imperfectly knovsm that little more 

 can be said about it. The occurrence of this highly specialized form, with 

 the equally specialized Pelycosaur Naosaurus, is strongly indicative of a 

 connection of the Old and New Worlds near the close of the Permian. As 

 indicated elsewhere, it is altogether probable that some members of the 

 American fauna migrated to Europe and continued their existence there 

 after the fauna had become extinct in America. 



COMPARATIVE TABLES. 



Table I. Showing the Characters of the Family Diplocaulidce. 



1. Skull large: triangular. Prosquamosal, parietal, supraoccipital and tabulare 



taking part in the formation of a large horn. 



2. Facial region abbreviate, not over one-fifth the length of the skull. 



3. Vertebrae complete, amphicoelous. Intercentra absent. Diapophysis and para- 



pophysis, intracentral. separate. Zygosphene and zygantrum present. 



4. Ribs two-headed; intravertebral. 



5. Teeth conic; dentine not inflected; a large pulp cavity present. 



6. Clavicle and interclavicle present, large, sculptured on outer surface. Coracoid 



small. 



7. Limbs present. Humerus with entepicondylar foramen (?). 



Table II. Contrasting the Characters of the Species of the Genus Diplocaulus. 



I. D. limbatus: 



1. Horns terminating in a point and curved inward at the end. The posterior 



edge of the skull more sharply concave. 



2. Anterior edge of frontal bone but little anterior to the orbits. 



3. Vomerine teeth arranged in a segment of a broad curve. 



4. Anterior end of the skull broadly rounded. 



5. Sculpture of facial region distinctly radial from a point between the orbits and 



nares. 



6. Orbits larger. 



II. D. magnicornis: 



1. Horns terminating more bluntly or with spatulate ends, not incurved at extremi- 



ties. Posterior edge of skull widely concave. 



2. Anterior edge of frontal bone nearly midway between the orbits and nares. 



3. Vomerine teeth arranged in a wide V, with the apex forward. 



4. Anterior edge of skull more acute. 



5. Sculpture of facial region not distinctly radial. 



6. Orbits smaller. 



HI. D. copei: 



Not determinate. 



IV, D. pusillus. 



Not determinate. 



