248 Tertiary. 



a lacustrine formation of Eocene age, though having examined an out- 

 crop for forty miles, he discovered no fossil remains except fossil wood. 

 He said the material is so easily transported that the drainage chan- 

 nels are cut to a great depth, and the Puerco river becomes the recep- 

 tacle of great quantities of slimy-looking mud. Its unctious appear- 

 ance resembles, strongly, soft soap, hence the name Puerco., greasy. 

 These soft marls cover a belt some miles in width, and continue at 

 the foot of another line of sandstone bluffs, which bound the immediate 

 valley of the Puerco to a point eighteen miles below Nacimiento. 



This section of the Eocene strata in the region west of the Sierra 

 Madre Range in New Mexico consists of green and black marls, which 

 he named the Puerco Group, 500 feet; sandstone of the Wasatch Group 

 1,000 feet, and red and gra_y marls of the same group, 1,500 feet; mak- 

 ing a total thickness of 3,000 feet. 



He described,* from the Eocene of New Mexico, Ambloctoims sin- 

 osus, Prototomus secundarius, P. muUicuspis, P. streiiuus, Dkicodon 

 alticuspis^ D. ccelatus, Pelycodus frugivorus, Pantolestes chdcensis, 

 Opisthotomus astutus, O. flagrans, Antiacodon mentalis, A. crassus, 

 Hyrachyus singularis, Ilyracotherium tapirinum, H. angustidens, H ^ 

 cuspidatum, Bathmodon latidens, B. cicspidatus, Diplocynodus 

 sphenops, Crocodilus grypus, C. wheeler i, and Dermatemys (f) 

 costilatus. 



He described,! from the Miocene of Cumberland county, New Jersey, 

 Phasganodus gentryi, Sphyroenodus silovuinus, and Agahelus porca- 

 tus ; from Flower's marl pit, Duplin county, North Carolina,^ Pristis 

 (Utenuatus ; from Edgerton's plantation, in Wayne count}^ Pneuma- 

 tosteus nahunticus ; from Halifax county, 3fesoteras kerrianus, and 

 Delphinapterus orcinus. From the Loup Fork Group of New 

 Mexico,§ PUauchenia humphreysana, P. vulcanorum, Hippotheri- 

 um calamarium, and Aphelops jenezanus ; and from the Pliocene of 

 the West, Canis tirsinus. 



Prof O. C Marsh|| described, from the Eocene of Wyoming, Lemu- 

 ravus distans, TiUotherium fodiens ; from Utah, Diceratherium ad- 

 venum, Diplacodon elatus, OroMppus uintensis, and Agriochcerus 

 pumilus. From the Miocene bad lands of Nebraska, Laopithecus ro- 

 bustus, Anisacodon montanus ; from the John Day river in Oregon, 



* Geo. Sur. W. 100th Meridian, Syst. Catal. of Vertebrata. 

 t Proc. Am. Phil. Sci., vol. xiv. 

 X Geo. of N. Carolina. 



I Proc. Aead. Nat. Sci. 



II Am. .Jour. Sci. and Arts, 3d ser., vol. ix. 



