UlNTACRINUS: ITS STRUCTURE AND RELATIONS. 3 



was stemless, and showed that the base consisted of one circlet of basals 

 surrounding an undivided pentagon. 



In 1893 W. B. Clark ^ gave a more extended description of U. socialis, 

 and made a detailed comparison of the species with U. westfaUcus. 



In 1894 Dr. S. W. Williston and Mr. B. H. Hill t gave an account of 

 some new and much more perfect specimens, found by Mr. E. E. Slosson in 

 Logan County, Kansas. These were the first that had been found in place 

 and Tuiweathered. Williston's account of this discovery is as follows: — 



^' While all the colonies hitherto discovered have been exposed and 

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

 by a soft blue shale. The animals had lived so closely together that their 

 very long arms had become inextricably entangled, and by consolida- 

 tion 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. . . . 

 The calices all lie flattened out, showing in some cases the basal plates, 

 but, as might be expected, never the upper or ventral portions. The in- 

 terlacing of the arms prevents the tracing of any to the extremity." 



Hill described the base as being constructed of " a small, five-sided, 

 centrodorsal plate, around which are grouped five pentagonal basals ; " 

 and he said that the "interradials" were usually seven, and interdistichals 

 two in number. Hill's figure is in some respects incorrect and misleading. 



In 1898 Mr. W. N. Logan ij: published a ^^ revised description " of 

 U, socialis, and gave a new figure, w^hich added nothing, however, to 

 the previous knowledge of the genus or species. 



In the meantime Mr. Martin found a deposit of very small specimens, 

 most of which were secured for the Kansas University Museum. He also 

 discovered, about the same time, another colony of Uintacriniis socialis in 

 place, some of which were acquired by the British Museum, and formed 

 the subject of Mr. Bather's paper of December, 1895, already mentioned. 

 A large slab from this find was also acquired by Prof. 0. C. Marsh, for 

 the Yale College Museum, and a description of it was given by Prof. 

 C. E. Beecher, § who found nothing in the specimens to throw new liglit 

 upon the structure of this Crinoid. All of the specimens of U. socialis, 

 except the one from the Uintah Mountains, have thus far been found 



* Bull. U. S. Geol. Surv., No. 97, pp. 21-24. 



t Kansas University Quarterly, Vol. III., No. 1, pp. 19-21. 



X Kansas University Geol. Surv., IV., p. 481. 



§ Am. Jour. Sci., April, 1900, p. 267. 



