Notes on Uintacrinus socialis Grinnell. 



While a member of the late Professor Mudge's party in western 

 Kansas, during the summer of 1875, the writer was fortunate in find- 

 ing in the Niobrara chalk a number of specimens of a crinoid which 

 were notable from their very rarity. During that same season, 

 whether before or after I do not now remember, other specimens 

 of the same kind were discovered by Prof. Mudge and Mr. Geo. 

 Cooper, all of which, as well as those found by myself, had been more 

 or less exposed and weathered. A very few of these found their way 

 into different collections, and among them were those which serve as 

 the types of genus and species.* An imperfect specimen of this genus 

 had been previously discovered by Marsh in the Uinta Mountains, 

 but so incomplete that its affinities could not be decisively made out. 

 ("In a stratum of yellow calcareous shale which overlies the coal 

 series conformably, a thin layer was found full of Ostrca congesta 

 Conrad, a typical Cretaceous fossil; and, just above, a new and very 

 interesting crinoid, allied apparently to the Alarsupiics of the En- 

 glish chalk." Marsh, Amer. Journ. Sci., March, 1871.) Because of 

 this previous discovery, the generic name was chosen, but there is no 

 proof that the species, at least, are identical. 



• During the season of 1891, Prof. E. E. Slosson, while a member of 

 the Kansas University expedition in western Kansas, was so fortu- 

 nate as to discover a most remarkable colony of this crinoid, by far 

 the best yet known, in the vicinity of Elkader, on the Smoky Hill 

 river. While all the colonies hitherto discovered have been exposed 

 and more or less weathered, the present one was found in position, 

 covered by the soft blue shale. The animals had lived so closely 

 together that their very long arms had become inextricably entangled, 

 and, by consolidation, had formed a dense calcareous plate, 

 about one-third of an inch in thickness in the middle of the plate, 

 but thinning out at the margin. About one-half of the thin slab as 

 thus formed had been washed away; the remainder, as now restored 

 in the University Museum, measures about six feet by three or four, 

 and has, upon its under side, nearly one hundred of the crinoids, 

 the greater part of which are perfectly preserved. The calyces all 

 lie flattened out, showing, in some cases, the basal plates, but, as 

 might be expected, never the upper or ventral portions. The inter- 



*(!rinnell. Anier. Journ. St-i. xii. Hi. July. 1S76. 



(19l KAN. UNIV. gUAH , VOL Ul. Nd. 1, .JUl.V. 1H9J. 



