THE MISSISSIPPIAN PERIOD. 519 



politanism. The fauna of the first epoch in the interior basin, the 

 Kinderhook, belongs to the provincial rather than to the cosmopolitan 

 class; for east of the Cincinnati arch there was a rather distinct fauna, 

 the Waverly, and in the Great Basin a fauna that was largely Devonian 

 in type still lingered in measured isolation, taking on slowly a Mississip- 

 pian aspect. The Kinder hook fauna proper was merely the leading 

 fauna of the interior, occupying the great Mississippian sea, and vary- 

 ing from region to region in response to the different physical condi- 

 tions already mentioned. 



The Kinderhook Fauna. 



One of the more important features of the evolution of the Kinder- 

 hook fauna was the progress of the fishes, in which sharks were the 

 leaders; but it will be more satisfactory to treat the fishes of the whole 

 period together after the less roving invertebrate faunas of the several 

 epochs are considered. 



The resilience of the crinoideans. — The departure of the Kinder- 

 hook fauna from the parent Devonian fauna is shown markedly in 

 the evolution of the crinoids, although, except locally, fossils of these 

 animals are of rare occurrence. They had a very scant development 

 usually throughout the Devonian, and were, in general, quite subordinate 

 to the corals; but in the Mississippian period the relative importance 

 of these groups was reversed. The crinoids not only forged ahead in 

 numbers, but they took on advanced characters. The beginning of 

 this deployment took place in the Kinderhook, and it reached its 

 climax in the next epoch, the Osage, where it will be more fully 

 noticed. Representative forms are shown in Fig. 235, e and /. Several 

 genera of blastoids were present, all different from those of the Devo- 

 nian faunas, but they were not as yet abundant, a fact the more 

 notable because of their remarkable development before the close of 

 the Mississippian period. The echinoids and asteroids were still less 

 abundant, a fact in harmony with their very modest development 

 throughout the whole Paleozoic era. 



Transition in the aspect of the brachiopods. — The brachiopods of 

 the Kinderhook fauna possess characteristics transitional between 

 those of Devonian and Mississippian types. Among them, the genus 

 Productus was conspicuous (Fig. 235, o). The Kinderhook species 

 may be said to be anticipatory of the typical Mississippian types, 



