1896.1 Idl [Cope. 



indicates a somewhat different generic reference to that which I have 

 hitherto adopted, as the generic characters have only now become clear 

 to me. The following are the generic characters as I now understand 

 them : 



I. Posterior maxillary teeth transverse, depressed, molariform, the 

 heel (external above, internal below) broad and flat. 



Skull without dermal or osseous sutures Empedias Cope. 



II. Posterior maxillary teeth compressed, transverse, with non-molari- 

 form edge or apex, except on wear. 



a Teeth with an external heel, besides the apical cusp. 

 Cranial bones coossified ; dermal scuta few or none Diadectes Cope. 



aa Teeth with a cusp only. 



Adult cranium sutureless Bolhodon Cope. 



Cranium with osseous but no dermal sutures Phanerosaurus V. M. 



Cranium with both osseous and dermal sutures Cliilonyx Cope. 



The species of these genera are the following : 



Empedias fissus Cope. 



" molaris Cope. 

 Diadectes sideropelims Cope. 



" phaseoUnus Cope. 



" latibuccatus Cope. 

 hiculminatus Cope. 

 Bolhodon tenuitectus Cope. 

 Phanerosaurus naumannii Von Meyer. 



" pugnax Gein. u. Deiclim. 



Chilonyx rapidens Cope. 



The above species are from the Permian bed of Texas, excepting the 

 two species of Phanerosaurus, which are from the corresponding horizon 

 in Germany. This genus displays the hyposphen-hypantrum articula- 

 tion in a less perfect degree than it appears in the American genera 

 where it is known, but it is nevertheless present. It presents conspicu- 

 ously other characters of the family in the broad closely articulating 

 neural arches, and short, robust neural spines 



PROC. AMEI?, PHILOS. SOC. XXXV. 151. Q. PRINTED AIGUST 13, 1896. 



