LFXANOCRINIDAE 135 



surface ornament is prominent enough to show in the double-sized figures without further 

 magnification as is necessary in L. facietatus, and if that character is of any value in this 

 group the two species are distinguished by it, as well as by the thicker walls. The principal 

 specimen has some indication of the depressed areas on the plates shown in Angelin's figures 

 of L. facietatus. 



Types. In the Riks Museum, Stockholm, Sweden. 



Horizon and locality. Silurian, Wenlock Group, bed d ; Hoberg, Gotland. 



Lecanocrinus pisiformis (Roemer) 

 Plate I, figs. 14-36 



Poteriocrinus pisiformis Roemer, Silur. Fauna Westlichen Tennessee, i860, p. 54, pi. 4, figs. ja-d. — 

 Shumard, Trans. Acad. Sci. St. Louis, II, 1866, p. 392.— Hall, 20th Rep. N. Y. St. Cab. Nat. Hist., 

 1868, p. 324; Rev. Ed., 1870, p. 366. 



Arachnocrinus pisiformis, Meek and Worthen, Geol. Surv. Illinois, II, 1866, p. 177. — Wachsmuth and 

 Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 94. — Miller, N. A. Geology and Palaeontology, 

 1889, p. 224, text-fig. 248; 17th Rep. Geol. Surv. Indiana, 1892, p. 651 (Adv. Sheets, p. 41). 



Cyathocrinus pisiformis, Whitfield, Geology Wisconsin, IV, 1882, p. 353. 



Lecanocrinus pisiformis, Wachsmuth and Springer, Revision Palaeocrinoidea, pt. 3, 1886, p. 227.— 

 Pate and Bassler, Proc. U. S. Nat. Mus., XXXIV, 1908, p. 419. 



Lecanocrinus hcmisphericus Rowley, Amer. Geologist, 1904, p. 281, pi. 16, figs. 17, 18, 19. 



A small species. Crown subglobose, widest about the middle of RR; in 

 25 specimens the average height at top of RR to greatest width is I to 1.3; 

 constricted distally, so that the average height to width of 12 specimens at IAx 

 is 1.3 to 1 ; base rounded. Calyx walls thin. Surface generally smooth, but 

 good specimens show a very fine granular network seen only under a strong 

 magnifier. Height and width of complete crown in average specimen, 8 by 

 8 mm. ; maximum specimen at top of RR, 9 mm. high by 1 1 mm. at middle of 

 RR; minimum specimen at same level, 3.5 by 4, and at IAx, 4.5 high by 3 wide; 

 width of column facet, 2 mm. 



IBB small, not protuberant, scarcely visible in side view. BB small. Anal 



x long, narrow, once and a half as long as wide, projecting not over about a third 



of its length above the radials. RR large, four times higher than IBr, and 



equaling the total height of the folded brachials. Height of B to R to IBr, 



3:4:1; large specimen 4.5 : 5:1. IBr 2. Arms short, flat, diminishing rapidly; 



second bifurcation not visible in folded crown. Column facet indented. Column 



small ; proximal columnals very long, without intercalated plates. 



This species, chiefly from the late Niagaran limestone of Tennessee, bears the same 

 relation to L. pusillus of the Waldron shales that L. facietatus does to L. billingsi in the 

 Wenlock beds of Gotland. It has always been considered a rare crinoid, until Professor Pate 

 in the summer of 1906 collected for me about 225 specimens, mostly from a single locality. 

 Notwithstanding its rarity, however, it has been from the time of Roemer a well-known 

 fossil to the various paleontologists who have collected in that region. The species has a 

 peculiar facies by which it is readily recognized. When the arms are attached the crown is 

 almost a perfect sphere, somewhat constricted at the upper end. The calyx to the upper mar- 

 gin of the radials is three-fifths of the total height of the crown, and the arms are so short, 

 rapidly tapering and infolding, that the second bifurcation is rarely seen — the plates closing 

 in at the summit being the secundibrachs. This juvenile character prevails throughout all the 



