480 University of Kansas Geological Survey. 



THE NIOBRARA FAUNA. 



The Niobrara species are numerous and varied. They repre- 

 sent forms ranging in size from the microscopic rhizopod to 

 the large bivalve mollusk, the Radiolites. Species belonging to 

 six of the invertebrate subkingdoms are found. These are rep- 

 resented by about twelve genera and more than thirty species. 



In the lower horizon, that of the Fort Hays limestone, fossils 

 are not abundant, especially in the lowermost beds. Those 

 forms found are Ostrese and Inocerami, and these occur for the 

 most part in the upper portion of the formation. The lower 

 Ornithostoma beds, and possibly the upper Fort Hays, contain 

 the large Radiolites, which are usually found in colonies. There 

 are also the immense Haploscaphse, with their adhering forms of 

 Ostrea congesta, and the broad, flat Inocerami, measuring three 

 or four feet in height. Numerous other species of Inocerami, 

 much smaller, are also abundant, Avhile the Uintacrinidse, with 

 their ball-like bodies and long-tentacled arms, occur more rarely. 



In the Hesperornis beds Ostrese occur, but are not particularly 

 abundant. Crustaceans are represented to the extent of at least 

 two genera and twice as many species. These belong to the 

 small cirriped type, and are not abundant. Inocerami repre- 

 senting still smaller species than those in the lower beds are the 

 most abundant types of this horizon. The chalk of which these 

 beds are formed is chiefly composed of protozoa and coccoliths. 



It is more than probable that in time a much larger list of 

 invertebrate forms will be found in the Niobrara beds of Kansas, 

 since, as yet, but little systematic collecting has been done. But 

 since, as yet, the Colorado formation has not been separated into 

 faunal divisions corresponding to its stratigraphical divisions by 

 the American invetebrate paleontologists, but has had its faunas 

 grouped as a whole, it is impossible to say what part of the 

 already described species belongs to the Niobrara division, or 

 what ones are likely to be found in our Kansas fields. 



