NATURAL SCIENCES OF PHILADELPHIA. 10i* 



Oct. 4th. 

 The President, Dr. Ruschenberger, in the Chair. 

 Twenty-nine members present. 



Prof. Leidy directed attention to a small collection of fossils recently re- 

 ceived from Prof. F. V. Harden, now engaged in a geological exploration of 

 part of our western territories. 



Most of the fossils were collected on the Sweet Water R., eighteen miles 

 west of Devil's Gate, Wyoming Territory. 



The most numerous and characteristic remains in the collection are those 

 of a species of Merycochozrus, the skull of which was little more than two- 

 thirds the diameter of that of Merycocho&rua proprius from the head waters of 

 the Niobrara River. The species is particularly indicated by a number of 

 fragments of jaws, with teeth of half a dozen individuals. The anatomical 

 characters are the same as in M. proprius. The infra-orbital arch is of great 

 proportionate depth, as in the latter when compared with its condition in the 

 different species of Oreodon. The face has the same abruptly contracted char- 

 acter in advance of the orbits, and the infra-orbital foramen occupies a cor- 

 responding position as in M. proprius. In Oreodon the face narrows more grad- 

 ually forward, and has a more triangular outline when viewed from above; 

 and the infra-orbital foramen is situated farther forward. There may be other 

 important anatomical points distinguishing Merycochozrus from Oreodon, in 

 portions of the skull of the former, which we have not yet had the opportu- 

 nity of examining. 



The inspection of these specimens leads me to suspect that the remains from 

 the pliocene sands of the Niobrara River, which I referred to another genus 

 under the name of Merychyus medius, perhaps belong to the same animal, and 

 those from the same locality referred to Merychyus major, perhaps belong to 

 Merycochozrus proprius. The material at command is insufficient for me to de- 

 termine whether this is the case, and under the circumstances I am disposed 

 to refer the remains in question, from the Sweet Water R., to a distinct species 

 with the name of Merycochcsrus rdsticus. 



A series of lower molars of this species measures 1 inches. 



A series in another individual * inches. 



The series in M. proprius is 5f inches. 



It has occurred to me that the remains thus referred to a smaller species of 

 3Ien/cochcerus, may have pertained to the female of 31. proprius. The speci- 

 mens, however, of all the individuals, indicate a smaller animal than those 

 upon which the latter was founded. 



In association with the remains are a few fragments indicating a small 

 equine animal, perhaps a Eipparion. There are also several small fragments 

 of jaws indicating the presence of Canis vafer and Merycodus necatus, origi- 

 nally based on specimens from the pliocene sands of the Niobrara River, Ne- 

 braska. 



The remaining fossils consist of two interesting specimens, from near tor 

 Bridger. One of them is an upper back molar, apparently of a small 

 specTes of Lophiodon. The crown of the tooth is perfect and but slightly worn 

 at the acute summits of the lobes. The tooth has nearly the form, size, and 

 constitution as the corresponding ones in Anchitherium Bairdi, but the ridges 

 extending forward and outward from the inner lobes in advance of the outer 

 lobes exhibit no trace of a disposition to form intervening lobes to the four 

 principal ones. The fore and aft diameter of the specimen is a little over 

 seven lines; the transverse diameter a little under that measurement, for 

 the name of the species I would propose that of Lophiodon modestus. 



The other specimen consists of a portion of the right ramus of a lower jaw 

 of a small pachydermous animal, containing the true molars, much worn 



1870.] 8 



