MISSISSIPPIC PERIOD 549 



Glen), the Mississippian sea united across the Kankakee axis with the 

 northern Appalachian waters and the eastern extension of the Cordilleran 

 sea. The faunas of the southern area were derived from the Gulf of Mex- 

 ico, which retained many of the descendants of the previous Hamilton 

 fauna. Other forms are also in harmony with those of western Europe. 

 Toward the close of the Kinderhookian the three provinces, formerly 

 separated, were united, and the Mississippian sea became more general. 

 Weller states : 



"With the submergence of the Kankakee Peninsula and the partial or com- 

 plete submergence of the Ozark land, the source of the clastic sediments in the 

 immediate Mississippi Valley was removed, and a great period of limestone 

 formation was initiated which is best exemplified in the Burlington and Keokuk 

 formations. The fauna of this clear sea was in large part an outgrowth of the 

 later Kinderhook faunas, and is best characterized by the wonderfully rich 

 [and indigenous] crinoidal element" (1909, 275). 



The Rockford formation has a fauna of Gulf origin and is marked by 

 the goniatites Prodromites prcematurus, Prolecanites greeni, P. lyoni, 

 Aganides rotatorius, Muensteroceras oweni, and M. parallelum. In the 

 Choteau, the following goniatites are also of southern origin: Prodro- 

 mites goroyi, P. ornatus, Prolecanites gurleyi, Pericyclus olairi, Aganides 

 ■discoidalis, A. jessieoe, and Muensteroceras osagense. 



The Osagian epoch followed the Kinderhookian, and introduced the 

 widespread Burlington limestone, replete with Echinodermata. In the 

 Paleozoic, starfishes are always rare, and they are so here, but the echi- 

 noids and blastoids are more common. The crinoids, however, are abun- 

 dant and highly differentiated, nearly 400 species being known from the 

 Burlington alone, most of which are found in the vicinity of Burlington, 

 Iowa. This crinoidal assemblage is here indigenous, this being an area 

 prolific in generating crinoids, but in free communication with the Gulf 

 of Mexico and western Europe. "Every genus in the Mountain Lime- 

 stone occurs also in the American faunas . . . ; furthermore, all of 

 those genera which occur in both this Mississippian province and in Eu- 

 rope are represented by a larger number of species in America" (Weller, 

 1909, 276). The connection is with the Atlantic and western Europe — 

 England and Ireland — but especially with the Tournacien series of Bel- 

 gium, the fauna of which is nearly all derived from the large quarries in 

 the vicinity of Tournai. 



Above the Burlington is the Keokuk limestone, which in the north and 

 east is more clastic, and often with much shale, but in the south the clear 

 water seas continued, introducing a horde of sharks, as shown by the teeth 

 of these fishes, which are here far more numerous than at any other 



