545 



[Cope. 



First Addition to the Fauna of the Pitereo Eocene. By E, D. Cope. 

 {Read before the American Philosophical Society, Jan. 5, 1SS3. ) 



There are fifty -five species included in my synopsis of the vertebrata of 

 the Puerco epoch*. Ten of these are reptilia, the remainder mammalia. 

 In the present paper a number of interesting additions are made. The 

 typical specimens are figured in the fourth volume of the U. S. Geological 

 Survey of the Territories, now ia press. 



Ophidia. 

 Helagras prisciformis, gen. et sp. nov. 



Char. gen. The generic characters are drawn from vertebrae only. 

 These display a modified form of the zygosphen articulation, as follows : 

 The roof of the zygautrum is deeply notched on each side of the median 

 line so as to expose the superior lateral angles of the zygosphen. This 

 separate median portion of the roof of the zygantrum torms a wedge- 

 shaped body which may be called the episphen. It is surmounted by a 

 tuberosity, which constitutes the entire neural spine. The latter is thus 

 entirely different in form from that of other serpents. Articular extremi- 

 ties of centrum round, the ball looking somewhat upwards. Costal arti- 

 culation 8-shaped, the surfaces convex and continuous. Hypapophyses 

 none on the two vertebrse preserved. Zygapophyses prominent. Free 

 diapophyses none. 



This genus is readily distinguished by the presence, now first observed, 

 of the episphen in addition to the zygosphen ; and by the peculiar form of 

 the neural spine. We have now several vertebral articulations originally 

 discovered in American vertebrata. These are the episphen as above, the 

 hyposphen, which characterizes the Opisthocoslous Dinosauria (Sauropoda 

 Marsh), and the Diadectidm of the Permian period ; and the zygantra- 

 pophysis, which is present in the Diplocaulid familj' of Batrachia. 



Chai: specif. A section of the vertebra at the middle is pentagonal, the 

 inferior side slightly convex downwards. The lateral angle is the section 

 of the angular ridge which connects the zygapophyses The episphen has 

 a shallow rounded groove on its infero-posteriorside, which is bounded by 

 a projecting angle on each side at its middle. The episphen does not pro- 

 ject so far posteriorly as the postzygapophyses, and the degree of its prom- 

 inence differs in different parts of the vertebral column. In one of the 

 two vertebrae in my possession its prominence is small. The tuber- 

 osity on its summit is a truncate oval wifh the long diameter anteropos- 

 terior, and equaling two-fifths the length of the arch above. It is ele- 

 vated above the rest of the median line, which is roof-like, with obtuse 

 angle. The tubercular articular facet is entirely below the prezyga- 

 pophyseal surface, but the free part of the prezygapopkysis extends well 

 in front of it. It is distinguished from the capitular surface by a very 

 slight constriction. A slight ridge extends from the capitular articulation 



* Paleontological Bulletin No. 35, Nov. 11th, 1S82. 



