1895.] 



MR. F. A. BATHER OX UIiS'TACRINTJS. 



977 



circlet of basals ; the interradial and interdistichal areas were 

 fairly visible all round the specimen, and though " the contour 

 and disposition of the plates differed in the different interradii," 

 there was no such variation as to point to the existence of a 

 special anal series. It is chiefly in the arrangement of the inter- 

 radial plates that this species differs from U. socialh. 



Kg. 3. 



Uintacrimis wesffalicus, tjpe-sjjecitnen from the Lower Senonian of Eeckling- 

 hausen, now in the Museum of Bonn University, a, from the side ; h, from 

 below. The illustration, re]3roclucecl from Zittel (5) P- 374 & (11) p. 1.3!), 

 by kind permission of Prof. Karl von Zittel, is a reversed copy of Schlueter 

 (4) pi- iv. figs. 1 & 2, reduced to i naturiil size, not natural size as invariably 

 stated. 



The American species was more fully described by W. B. Clark 

 in 1893 (8), but his specimens did not throw much more decided 

 light on its structure (PI. LVI.). Tn the following year, however, 

 S. W. Williston and B. H. Hill (9) published some notes on speci- 

 mens discovered in 1891 by Prof. E. E. Slosson. These specimens 

 were the first among those found in America to show the base with 

 the desired clearness, and were in other respects far superior to 

 any specimens of U. socialis previously collected. They were found 

 near Elkader, on the Smoky Hill Eiver, W. Kansas, and their 

 mode of occurrence is thus described by Prof. Williston : — " 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 underside 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 interlacing of the arms prevents the tracing of any 

 to the extremity." 



