J40 SMITHSONIAN INSTITUTION 



Lecanocrinus meniscus n. sp. 



Plate I, figs. 3/a-c 

 A small species. Crown subovoid, widest at lAx; broadly truncate below, 

 and obscurely pentagonal at level of IBr; base broad; height to width at IAx, 

 i to 1.6; at RR, I to 2.5. Calyx plates thick; surface apparently smooth. Incom- 

 plete crown, 11 mm. high at IIBr 3 by 11 mm. wide at IAx; width of base at trun- 

 cation, 6.5 mm. ; width of column facet, 3 mm. 



IBB very small, entirely concealed by the column. BB large, but only seen 

 as pentagons in a side view, the lower part being abruptly bent inward by the 

 truncation of the base almost at a right angle toward the column. Anal x very 

 large, obtusely angular, and rising with a 10-sided figure more than half its 

 height above radials to the level of the first primibrachs. RR small, only once 

 and a half the height of IBr, upper margin widest; height of B to R to IBr, 

 3.5 : 4.5 : 3. IBr 2, large, more than half as high as the radials and increasing in 

 width upward; somewhat gibbous, depressed at the sutures and rounded longi- 

 tudinally, making the cross-section at their level quinquelobate. Arms un- 

 known beyond IIBr 3 . Column much smaller than the truncate base, unknown 

 beyond proximal columnals which are short. 



This species is described from a single specimen which is remarkably distinct from all 

 other known species. The character of the base alone distinguishes it ; the concealed inf ra- 

 basals and truncate basals constitute a departure from the prevailing habitus of the genus. 

 The brachial series is of an intermediate character in that the radials and primibrachs are less 

 differentiated, and increase more uniformly in width upward than in the typical Lecanocrinus. 

 In this character it falls into a group with L. bacchus and L. angulatus; and with the latter 

 alone it agrees in the great height to which the anal x rises. It is a very robust form with 

 thick and heavy plates, in the convexity of which it also differs from other species. 



The unique type specimen was found in debris of the Astraeospongia bed of the Meniscus 

 limestone, according to Safford's section of the rocks of western Tennessee, now known in 

 part as the Brownsport beds. 



Type. Author's collection. 



Horizon and locality. Silurian, Brownsport limestone (part of the Meniscus beds) ; 

 Decatur County, Tennessee. 



Lecanocrinus waukoma (Hall) 

 Plate III, figs. 20-25 



Cyathocrinus waukoma Hall, Adv. Pub. 18th Rep. N. Y. St. Cab. Nat. Hist. 1865, p. 20, pi. (2), figs. 11, 

 12; reprinted in 20th Rep. N. Y. St. Cab. Nat. Hist., Doc. Ed., 1868, p. 324, pi. 11(2), figs, ir, 12 

 (Revised Ed., 1870, p. 367, pi. 11, figs. 11-12). — Wachsmuth and Springer, Revision Palaeocri- 

 noidea, pt. 1, 1879, p. 87. — Chamberlin, Geol. Wisconsin, I, 1883, p. 191, fig. 50/. — Bather, Ann. and 

 Mag. Nat. Hist. (6) IX, Mar. 1892, p. 213; Crin. Gotland, Sv. Vet. Akad. Handl., XXV, 1893, 

 p. 127. 



Lecanocrinus waukoma, Weller, Bull. IV, Chicago Acad. Sci., pt. 1, 1900, p. 148, pi. 15, figs. 6-10; not 

 fig. 11. 



Lecanocrinus pusillus, Winchell and Marcy (not Hall, 1863), Mem. Boston Soc. Nat. Hist., 1865, p. 90. 



A large species. Calyx low, subhemispheric, rotund below, with nearly 

 vertical sides and flat or concave base ; widest about middle of radials, average 



