SAGENOCRINIDAE 259 



Steinmann's proposal to refer this species to a new genus, Proguettardicrimts, on 

 account of superficial resemblance to the Jurassic Guettardicrinus has been discussed in the 

 chapter on Phylogenetic Relations. 



Types. The original type is in the University of Chicago ; that of figures la, b is in the 

 author's collection. 



Horizon and locality. Lower Carboniferous, upper part of Keokuk Group; Edwards- 

 ville, Floyd County, Indiana. 



Forbesiocrinus saffordi Hall 

 Plates XXI, fig. 3; XXX, figs. 3-1/; XXXI, figs. 1-10 



Forbesiocrinus saffordi Hall, Supp. Geol. Iowa, I, pt. 2, i860, p. 87. — Wachsmuth and Springer, Revision 

 Palaeocrinoidea, pt. 3, 1886, p. 145. 



A very large species. Crown low, pentagonal, wider than high, contracting 

 rapidly above IIBr; greatest width at IIBri, where height to width is I to 2.8; 

 of calyx at upper limit of iBr, about I to 1.4; spread of calyx at upper limit of 

 iBr, about 1 to 1.4; spread of calyx from column facet, 1 to 4.7; height 

 (estimated) to width of crown, 1 to 1.26; of calyx to crown, 1 to 1. 1. Calyx 

 deeply lobed; cross-section quinquelobate ; side outline broadly curved. Base 

 flush with top columnal. iBr areas concave, large and long, with large plates. 

 Rays highly arched, broadly sloping to iBr areas. Calyx plates flush with the 

 general curvature, those of iBr areas concave, those of the rays broadly rounded 

 except the axillary IIBr, which is strongly tumid and abruptly curved at the 

 distal end, so that the next order of brachials start at a lower level. Post. B 

 truncate, followed by a single plate, and this by two or three abreast, increasing 

 to four or more abreast for several ranges; regular iBr also becoming four 

 abreast and extending to beyond IIIBn. Dimensions of successive plates in 

 millimeters: B, 5 x 10.5; R, 3X 14; IBr 2 , 12 x 17; IIEn, 8.5 x 14; IIBr 3 , 9x12; 

 IIIBr, 3x7.5; those following, 2x7.5. Dimensions of mature specimen 

 (PI. XXXI, figs. 1 a, b) ; height of crown estimated from curvature, 60 mm.; 

 of calyx, 55 mm. ; width, 76 mm. ; base at column facet, 16 mm. Same measure- 

 ments in young specimen (PI. XXXI, fig. 2): 21; 17; 35; 8. A still younger 

 specimen, preserved only to IIBri, is 7 mm. high by 18 mm. wide at that level; 

 base, 5 mm. A detached base, indicating a crown still larger than the above 

 mentioned specimen, is 18 mm. wide (fig. 3). 



The strong lobation of the calyx is the special character of this species, in which it 

 differs from all others. The great arching of the rays requires brachial plates of large size, 

 as the above figures indicate, and it produces such wide spaces between that the interbrach- 

 ials form broad concave areas, with relatively larger plates than in other species. Only at the 

 end of the secundibrach series do the plates lose their even curvature and become tumid ; and 

 the abrupt distal rounding of IIBr 3 is a feature by which the species can be identified from 

 any fragment preserving this part (PI. XXXI, fig. 5). Not only is the abrupt change of 

 the succeeding plates to a lower flat surface a very marked character but also the very great 

 disproportion in their size. Unfortunately none of the specimens have the rays preserved 



