SAGENOCRINIDAE 257 



smaller than the average of mature specimens in the two preceding" species. The 

 arms are flat and abutting, as in F. wortlicni, but are much shorter and more 

 delicate than in either. The calyx rises to a higher level, being to the crown as 

 1 to 1.4 in an average of five specimens, as compared with 1 to 2 and I to 1.6 in 

 F. wortheni and F. multibrachiatus respectively. The greatest width is at about 

 IIIBra, instead of IIBr.i as in those species, so the ratio of height to width is 

 about 1 to 1.5, as against 1 to 2 or 1 to 1.8. There is also a greater convexity of 

 the plates, which are rounded from the suture lines, and not merely raised in the 

 middle as in the Burlington species. In a maximum specimen the crown is 

 47 mm. high ; calyx, 35 ; width at IIIBr 2 , 44; base, 13. 



As already stated, Miller and Gurley described two species from this locality, the first 

 being F. speciosus, which I have doubtfully referred to F. multibrachiatus. They distin- 

 guished it from the present species by its supposed lack of distinct anal side, and also by its 

 having only 40 arms, against 60 in this ; being an application of Miller's favorite dogma that 

 the actual number of arms is an iron-clad specific character. Here the difference is due 

 wholly to the height at which the arms happen to be folded in the fossil ; if between the 

 third and fourth bifurcation, forty will be visible from the exterior; if beyond the fourth, 

 sixty or seventy or even more, according to the height of the infolding. 



Types. Miller and Gurley's originals are in the University of Chicago; that of figure 3 

 in the author's collection. 



Horizon and locality. Lower Carboniferous, Keokuk Group ; Canton, Washington 

 County, Indiana. 



Forbesiocrinus pyriformis Miller and Gurley 

 Plate XXIX, figs. 6-7 



Forbesiocrinus' pyriformis Miller and Gurley, Bull. 3, Illinois St. Museum, 1894, p. 47, pi. 4, fig. I. 



A large species. Crown elongate, pyriform, widest about IVBr, which is 



about the limit of the calyx. Height to width there i to 1.35; spread of calyx 



from base, 1 to 3.7; height of calyx to crown, 1 to 1.8; height to width of crown, 



1 to 0.75. Calyx conical, with straight sides, cross-section circular. Base flush 



with top columnals. Calyx plates tumid, suture lines sinuous and impressed. 



iBr areas elongate and narrow with plates numerous. Arms rounded, short, 



well separated. General arrangement and proportion of plates as in the three 



preceding species, except that the lower brachials are somewhat longer, making 



the interbrachial areas also more elongated. Crown of large specimen, 60 mm. 



high ; calyx, 35 mm. ; width, 50 mm. ; base at column facet, 13 mm. 



The distinctly conical, circular calyx, and deeply rounded arms distinguish the species 

 readily. It occurs in the Keokuk of Kentucky and Tennessee, where none of the preceding 

 have been identified, and it has not been found in their regions. The species is rare, only 

 four specimens being known, three of which are in the University of Chicago. Of these 

 four specimens, three have the posterior basal truncate, followed by a single plate interposed 

 between it and the usual two (PI. XXIX, figs'. 6b, jb), and that is probably the general rule 

 in the species. Beyond the IIIBr the arms begin to taper quite rapidly, and infold about the 

 fifth bifurcation. The zone of greatest width is at a higher order of brachials than in any 



