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Show 1895.] MR. F. A. BATHER ON UINTACRINUS. 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," tbere was no such variation as to point to the existence of a special anal series. It is chiefly in the arrangement of the interradial plates that this species differs from U. socialis. Fig. 3. Uintacrinus westj'aliens, type-specimen froui the Lower Senonian of Eecklino-- hausen, now in the Museum of Bonn University, a, from the side ; b, from below. The illustration, reproduced from Zittel (5) p. 374 & (H) p. 139, by kind permission of Prof. Karl von Zittel, is a reversed copy of Schlueter (4) ph iv. figs. 1 & 2, reduced to £ natural 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 (PL LVI.). In the following year, however, S. W . Williston and B. H . Hill (9) published some notes on specimens 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 Biver, 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 wreathered, the present one wa3 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." |
