SYSTEMATIC REVISION 



13 



"The affinities of this very singular form can not yet be determined. The 

 mandibular ramus rises directly from the posterior extremity of the dental series, 

 showing that there is a coronoid elevation of the bone, as in the Dinosauria. The 

 teeth are received in deep alveoli. It is probable that the vertebrae are amphicoelous. 

 The animals belonging to this genus were, in all probability, herbivorous." 



In the "Proceedings of the American Philosophical Society" for 1896, vol. 

 xxxiv, p. 441, Cope gave the presence of a canine tooth as the distinguishing mark 

 of Diadectes as opposed to Empedias. Later in the same year (Proc. Am. Phil. 

 Soc, vol. xxxv) he suggested the more depressed and molariform character of the 

 cheek teeth of Empedias as a distinguishing character. 



Genus EMPEDIAS Cope. 



(This genus is not determinable, but the description is introduced because in 

 it is given the character of the hyposphene and hypantrum.) 



Type: Numerous vertebrae, four in series. No. 435 1 Am. Mus. Nat. Hist. Cope 

 Coll. From Texas. 



Original description: "Both dorsal and cervical vertebrae possess centra of the 

 general character of Clepsydrops, with small intercentra. The neural arches present 

 important differences. There is on the posterior aspect, below the zygapophyses 

 a well-developed hyposphen, and on the anterior face a correspondingly strong 

 hypantrum. The structure is identical with that which I have described in the gen- 

 era Camarasaurus and Amphicalius, but is rather better developed. It disappears 

 at some posterior point of the dorsal series. The zygapophyses are much elevated, 

 and spread apart in Empedocles, and are connected back to back. From this 

 junction the diapophysis depends, forming a vertical septum whose inferior extent 

 is greatest on the cervical, and least on the dorsal vertebrae. It is undivided, and 

 there is no capitular facet on the centrum, the rib had but a single head. The 

 expansion of the diapophyses with that of the posterior zygapophyses gives to the 

 posterior side of the vertebrae a remarkable appearance, and forms an oblique roof 

 above the centrum. The neural spine is not elevated, and is very robust, being in 

 some cases greater in the transverse than in the anteroposterior diameter, again 

 approximating remotely, Camarasaurus. Of the dentition nothing is known, but 

 some jaws with teeth of animals allied to Clepsydrops may belong here." 



In 1880, from the study of three imperfect skulls, Cope adds the following 

 to the characterization of Empedias: "Molar teeth in one series. No canine." 



In 1883 he adds that "the species of Empedias form a series which diverges 

 from Diadectes by a successive widening of the crowns of the teeth and a diminution 

 in their number." 



In 1896, p. 441, he gives in a comparative table: "Teeth less compressed, 

 robust; no canine; os tabulare not produced; top of head without dermal scuta." 



In vol. xxxv of the "Proceedings of the American Philosophical Society" for 

 1896, p. 131, he gives a totally new classification of the Diadectidce and announces 

 the following characters for Empedias: "Posterior maxillary teeth transverse, 

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

 Skull without dermal or osseous sutures." 



Revised description: In addition to the characters given in the description of 

 the family and the order: 



1. Cheek teeth, from the middle part of the series, with three distinct cusps. 



The number of cheek teeth variable. Tooth line sigmoid. 



2. Skull with coarse, rugose sculpture; not tuberculate. 



