THE AMERICAN MUSEUM JOURNAL 



horizon of the Upper Cretaceous of western Kansas. This slab, 

 which is five feet four inches long and three feet two inches wide, 

 in extreme dimensions, has been mounted and is now on exhibi- 

 tion in Panel i of Case P on the west side of the Geological Hall 

 (No. 405) on the fourth floor of the Museum. 



Crinoids belong to the same great subdivision of the animal 

 kingdom as the common modern Starfish, but they are of a lower 

 grade of organization. Some forms are provided throughout life 

 with stalks, or stems, the lower ends of which are rooted in the 

 mud of the sea-bottom or attached to some foreign object. 

 Other forms, like the Comatida of the present seas, had such 

 stalks during the very early stages of their existence, but lost 

 them afterwards and floated free in the water. Crinoids seem to 

 have been most abundant both in species and in individuals, 

 during Lower Carboniferous (late Paleozoic) time, but, for the 

 most part at least, they were stalked forms, leading a stationary 

 existence. The free forms were more abundant later and now 

 are very numerous, more than two hundred species of the family 

 Comatulid£e having been described from the present ocean. 

 Uintacrinus was a free form and has been found only in beds 

 of Upper Cretaceous age. 



The first specimen of the genus was found in 1870 by Prof. 

 O. C. Marsh in the Uintah mountains in northeastern Utah. The 

 Kansas specimens have added very greatly to our knowledge of 

 these beautiful animals and have g ven Mr. Springer the material 

 from which he has been able to complete the morphological 

 studies of the genus made by Mr. F. A. Bather of the British 

 ]\Iuseum on European material. Mr. Springer's conclusions have 

 been published in an elaborate memoir by the Museum of Com- 

 parative Zoology of Harvard University with several plates. 



The investigations of Mr. Springer and others at the best 

 localities show that these Crinoids lived in populous colonies in 

 the quiet mediterranean sea or lagoon which occupied western 

 Kansas in Cretaceous times. Those Crinoids that were at the 

 lowest part of the floating mass rested directly upon the soft mud 

 and settled into it in the positions in which they happened to be 

 when the colony died. These were thus perfectly imbedded by 



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