568 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



istic of No. 4 in New Jersey, as is also the only species of Glidastes from 

 that region, neither having yet been found in No. 5. 



The following Mollusca which I jDrocured from this formation were 

 identified for me by Mr. Meek a short time before his death. A melan- 

 choly interest attaches to this work, as it is the last ever done by our late 

 colleague: — Inoceramus cripsii var. harabinii; Inoceramus, sp. uudet. ; 

 Baculites compressus Say (*?). 



A question remains as to the age of the light-colored (buff or white) 

 sandstone underlying No. 4. I did not procure any fossils from it, and 

 Dr. Hayden did not bring any from his early expedition to this region. 

 He states, however, that he has always been accustomed to regard it as 

 the Dakota, or No. 1. He describes it as constituting the bad lands be- 

 tween the Judith Basin and Fort Benton, which have been described 

 by Lewis and Clarke, Prince Neuwied, and others. I saw but an out- 

 lying portion of this region on the north side of the Missouri near to 

 Eagle Creek. The sandstone is not so hard as that of No. 1, which I 

 have observed in Wyoming, but resembles much that of No. 3 as it ex- 

 ists in New Mexico. Like No. 3, it is underlaid by a dark and soft shale 

 (see Fig. 2), which perhaps represents No. 2. Geographically consid- 

 ered, it is appropriately No. 3, since it occupies a region between that 

 occupied by Nos. 4 and 5, and Fort Benton, where No. 2 is extensively 

 exposed. Dr. Hayden expresses the view that Nos. 2 and 3 are wanting 

 from the region of the Judith (p. 128), and it is true that the lithologi- 

 cal character of this rock is different from that of No. 3 as seen in Ne- 

 braska and Kansas. 



The ferruginous soft sandstone of the Fox Hills group is everywhere 

 the line of demarkation between the black shales of No. 4 below and 

 the Judith Elver beds above. Its thickness is so much less than that of 

 the other formations that it seems to be less significant than either? 

 and there is nothing yet known of its Vertebrate palaeontology in the 

 West, of sufficient importance to warrant its separation /rom No. 4. 

 Lithologically, it is identical with several sandstone beds of the Judith 

 Eiver lacustrine series, althougli its fossils are marine. It is a soft 

 sandstone, varying from dark rusty to brownish buff' in color, usually 

 from 25 to 30 feet in thickness. At a locality on the high bank of a 

 small stream 10 miles west of Amell's Creek, I obtained the following 

 Vertebrate fossils from it: — 



Sauro'pterygia : — Uronautes cetiformis Cope, Proc. Acad. Phila., 1876, 

 p. 346, vertebrae, limbs, and ribs. 



Bhynchocephalia : — GJimnjpsosauriis, sp. indet., a single vertebra. 



Isospondyli: — JEJnchodus, teeth. 



JElasmohranchii: — Lamna and Otodus, sp. 



The Mollusca were identified by Mr. Meek^ and comprise the following 

 species. They are from several localities : — 



Baculites ovatus Say, northwest border of Judith deposit. 



Baculites ancejjs Say, Judith River. 



