190 GEOLOGY. 



immense numbers. Often, however, no trace of these organisms is 

 left. I found them where they had apparently been preserved from 

 crushing first beneath the huge scale of a fish, and then in the hol- 

 lows of reptilian vertebra. As in the European chalk, the spicula 

 of sponges are occasionally found in this group. 



This era was evidently well adapted to the support of molluscan 

 life, though the number of species is less than from the preceding and 

 the next two following. The number of individuals, however, is 

 enormous. One of the last tasks that the lamented Meek performed, 

 was the completion of his great work on the Invertebrate Palaeon- 

 tology of the Cretaceous, in which he described four species of 

 mollusks from this group. One of these was a species of oyster 

 (Ostrea congesta), which must have been very abundant, as remains 

 of it are found in every stratum of this group. An anomia is 

 found principally in Knox County. An oyster-like shell (Inocer- 

 amus problemalicus], and a variety of the same, are the most abun- 

 dant, some whole strata being almost entirely composed of it. The 

 Inoceramus bed is so named from the abundance of this shell. Re- 

 lated to these is a genus represented by two species which were re- 

 markable for their size. They were described by Conrad, and 

 named Haploscapha grandis and H. eccentrica. The former is of gi- 

 ; gantic size, being twenty-seven inches in diameter, and the latter 

 (nine inches. They are found in this group on the Republican, 

 Solomon and the Smoky Hill. In the stratum of yellowish impure 

 limestone beneath the Inoceramus bed there are many impressions 

 of ammonites and nautilus and other chambered shells. They are,, 

 however, so poorly preserved that it is impossible to identify them 

 with any certainty. One impression of an ammonite from the chalk 

 in the cabinet of the University is eighteen inches across. 



The seas of this era swarmed with fishes. In the chalk in Knox 

 and Cedar counties, for over a hundred feet through it vertically, 

 almost every spadeful of rock contains fish scales or teeth or both. 

 Many of the species were of reptilian type, or at least were pre- 

 daceous and allied to the modern saury or salmon. Cope has de- 

 scribed forty-eight species, most of which were from the Niobrara 

 Group in Kansas. Many of these I have identified from the same 

 group in Nebraska. One of the most abundant of these fishes, and 

 also one of the most rapacious that ever existed, is known as Por- 

 theus molossus. Cope. Its bones are sometimes found to project 

 from the sides of the limestone bluffs in the Republican Valley. 



