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Show 976 MR. F. A. BATHER ON UINTACRINUS. [Dec. 17, the Niobrara Chalk of Trigo Co., W. Kansas, associated with the Odontornitbes, Pterodactyls, and Mosasauroid reptiles of that formation. One of these crinoids, which was sent to the Vale College Museum, served Grinnell as the type of genus and species, Uintacrinus socialis, which he described in 1876 (2). The specimens studied by him showed neither base nor arms clearly (fig 1, p. 975). Some specimens sent at the same time from Prof. Mudge to F. B. Meek were well described by the latter (3), w ho added a few details concerning the interradial and interdistichal areas (fig. 2). Still there remained to be determined " the nature of the base (whether composed of five pieces surrounding a central piece, and whether or not it was connected with a column), the presence or absence of subradial pieces, and whether there is an anal series of pieces differing from each of [the other] interradial series." Fig. 2. Uintacrinus socialis. Reproduction of Meek's fig. B, in Bull. U.S. Geol. & Geog. Survey, ii. p. 375. " A flattened specimen, [in which] all the body-plates of one side are seen. The plates of one interradial area (middle of figure) [interbrachials, mihi] and parts of two others, one on each side, as well as those of two of tbe interaxillary areas [interdistichals, mihi], are shaded to distinguish them from the plates of tbe radial system [fixed brachials, •mihi], which latter are marked with dotted lines." Natural size. This specimen is in tbe U.S. National Museum, and has been re-figured by W . B. Clark (8). See page 982 and P L LVI. fig. 1 a. Almost contemporaneously a specimen of this genus, but representative of another species, was discovered in Europe at a slightly higher horizon, namely in the lowest division of the Lower Senonian, in the Marsupites zone, near Recklinghausen in Westphalia. This was exhaustively described and discussed by Schlueter in 1878 (4), under the name U. westfalicus (fig. 3). In this specimen the arms were not well preserved ; the base, which was clearly seen, confirmed the impression of previous writers hat the genus was unstalked, and showed that there was but one |