416 SMITHSONIAN INSTITUTION 



Types. Miller and Gurley's original is in the Walker Museum, University of Chicago. 

 The other specimens figured are in the author's collection. 



Horizon and locality. Lower Carboniferous, upper part of Keokuk Group, about 

 equivalent to the Geode bed ; Indian Creek, Montgomery County, and Canton, Washington 

 County, Indiana. 



Parichthyocrinus crawfordsvillensis (Miller and Gurley) 

 Plate LXIII, figs. 5-6 



Taxocrinus crazvfordsvillensis Miller and Gurley, Bull. 3, Illinois St. Mus. Nat. Hist., 1894, p. 49, pi. 4, 

 fig- 3- 



A very large species. Crown higher than wide, about 1.2 to 1. Calyx 

 greatly rounded, height to width at IAx about 1 to 2, evenly curved below. 

 Rays not very prominent, arms broad and flat, bifurcating four times; sutures 

 arcuate. iBr numerous, in several ranges of rather small plates; ill Br 

 present. Anal plates in a median series bordered on each side with numerous 

 strong irregular plates. BB fairly large, visible as triangles or pentagons 

 beyond column. iBr numerous, in large elongate areas. Surface smooth. 

 Column large, with conical taper of very thin columnals next to calyx, passing 

 into crenulated alternate ossicles which become uniform in lower half and 

 increase in length downward; irregular cirri toward the distal end, which 

 evidently terminated in a fine point without any branching. Crown in type 

 specimen, 50 mm. high by 40 mm. wide ; base, 1 1 mm. 



This species from the Crawfordsville, Indiana, beds at a higher horizon than the pre- 

 ceding, represents a modification toward a solid anal structure similar to what is observed 

 in species of Taxocrinus like T. ungula and T . giddingei; there is a median tube-like series, 

 but it is bordered by plates much stronger than ordinary perisome ; those adjoining the rays 

 are nearly as large as regular interbrachials, but those next to the tube are smaller and more 

 irregular. The only specimen we have showing the posterior side is crushed, and the 

 arrangement of these parts disturbed. The authors in describing the species compared it 

 with Forbesiocrinus multibrachiatiis of Lyon and Casseday, from which they had difficulty 

 in distinguishing it, but did so on the ground of the anal structure as follows (op. cit., 51) : 

 In our species the azygous area is larger than the regular interradial areas, and has a series of five 

 long longitudinally convex plates in the middle of the area, resting upon the truncated upper side of a 

 basal plate, and extending as high as the third secondary radial ; and on each side of this ridge of plates 

 there are several smaller polygonal plates, and others extending beyond. 



The similarity to F. multibrachiatiis is still stronger when we consider the specimens 

 of that species such as I have illustrated on Plate XXVIII, where there is a tendency to 

 differentiation of the median plates of the anal area in form of a tube ; and the presence of 

 numerous ranges of interbrachials — far more than observed in any other species of 

 Parichthyocrinus — must be also considered. It is a doubtful question, but I have been led 

 to retain the species here by reason of the decided flatness of the arms, and the fact that 

 F. multibrachiatiis does not otherwise occur in the Crawfordsville beds but at a different 

 horizon in the same formation, and also because the recent acquisition of a second specimen 

 from the same beds confirms fire general habitus. It is exceedingly rare, these being the 

 only specimens found among the many extensive collections made at that famous locality 

 during over fifty years. 



Types. Miller and Gurley's original is in the Walker Museum, University of Chicago ; 

 that of figure 6 in the author's collection. 



Horizon and locality. Lower Carboniferous, upper part of Keokuk group, above the 

 Indian Creek horizon ; Crawfordsville, Indiana. 



