392 [August, 



length. The eyes are rather small. The dorsal fin is longer than high; its 

 anterior margin situated almost at the same distance from the snout and the base 

 of the caudal fin. Caudal fin forked. Anal back of the dorsal. Base of ven- 

 trals behind the anterior margin of the dorsal; tip not reaching the anal fin. 

 Pectorals not reaching the base of ventrals. The pectorals, ventrals and anal 

 are proportionally small compared to the dorsal. 



D 9. A 8. C 3. I 8. 8. I 3. V 8. P 14. 



Scales large; lateral line running through the middle of the sides, slightly 

 bent downwards on the abdomen. 



Back brownish yellow ; a greenish grey stripe down each side covering the 

 lateral line. 



Caught in Otter creek, Arkansas. 



'o 



On leave granted, Dr. Leidy made the following communication : 



Dr. John Evans, who is now engaged under the United States government to 

 survey part of Oregon, recently sent to the Academy for examination, ten boxes, 

 containing alarge quantity of mammalian and chelonian fossils, from the Mauvaises 

 Terres of Nebraska. In this large collection, it is worthy of ren^ark, there is 

 not to be found a single fragment of a bird or a fish bone. Most of the animals 

 indicated by the remains, have already been described in Dr. D. D. Owen's 

 Geological Report, and in the " Ancient Fauna of Nebraska" of the author. The 

 collection contains several new genera and species of mammalia, besides frag- 

 ments of important parts not before obtained of those species described. 



A very large proportion of the collection consists of remains of Oreodun^ of 

 which tiicre are fragments of about two hundred individuals. The species O, 

 Cidhertsonii predominates, and then follows O. gracilis ; while of O. major 

 there are very few fragments. This enormous quantity of remains of Oreodun, 

 would indicate that the animal was gregarious, and existed in immense herds like 

 the recent Peccary or Bison. 



Only a few small fragments of Poehtotheriwm Wdsonii and Agriochoeins 

 antiqnus are contained in the collection. 



Of the two species of Kldnoceros^ R. occidentalis and K. Nehrasreyisis, there 

 are remains of numerous individuals. 



Of Eiitelodon Mortoni the collection contains portions of several crania. 

 Of Anchitherium Bairdii there are four crania and numerous smuU fragments 

 of others. 



Of the huge Titavotherium Prontii there are numerous small fragments ot 

 bones and teeth ; and also several entire superior molars, which have served 

 to remove some of the obscurity in regard to the characters of the ai.imal. From 

 the last mentioned specimens it appears that those, which have been desciibed 

 as probably indicating a new species o{ Palceotherij(7n, under the name P. gigaii- 

 teum, (Ancient Fauna of Nebraska, pi. XVII, figs. 11-13,) belong to Titanothe- 

 ritim Proittiiy while several superior molars (lb. figs. 1-7), attributed to the latter, 

 belong to a new genus associating characters of Rhinoreros and Pulcrotheriirm. 

 For this genus and species, represented by figures 1-7, plate XVII, in the .-Ancient 

 Fauna of Nebraska, I propose the name of Kotherium American tivi. 



Of Machairodics primaevus there are preserved several crania and some other 

 bones. 



Of the new mammalia above referred to, there are four carnivora and one rumi- 

 nant. The carnivora consist of three species of HycBuoduii and a new genus. 

 The ruminant is a new genus closely allied to the recent Mosihus, These 

 interesting animals I propose to name as foll-ows : 



1. Hy>enodon HORRiDUS, Leidy. This is the largest of the three species above 

 referred to. It is founded upon a much fract'ired sktill and lower jaw ; but on 

 both sides of the specimen the teeth are preserved nearl}'^ perfect. The formula 

 of the dentition is as follows: 



3 17 



in. c. mol. 

 3 I 7 



