400 SMITHSONIAN INSTITUTION 



In all collections and exchanges labeled by Wachsmuth the name Ta.vocrinus multi- 

 brachiatus Lyon and Casseday was applied to the fossil. The latter species, under the genus 

 Forbesiocrinus, had been described by Lyon and Casseday along with some other well- 

 known Crawfordsville species upon specimens said to be from Montgomery County, Indiana, 

 and other localities, but without any published figures ; as the description agreed in a general 

 way, the present abundant form was supposed to be the one intended. By this means their 

 name became established for the crinoid under consideration in the collection of the Museum 

 of Comparative Zoology at Harvard; and in that of Wachsmuth and Springer. Now 

 Lyon's species, multibrachiatus, as is clearly demonstrated by examination of his type speci- 

 men and by comparison with numerous other good specimens obtained in the same county, 

 but from another locality and horizon, is an entirely different thing, having a solid anal side 

 and being a true Forbesiocrmus. Hall's F. meeki also proves not to belong to this species or 

 genus, but to Parichthyocrinus. Therefore those two species are eliminated from considera- 

 tion in connection with this. 



In 1880 Dr. White, sharing Wachsmuth's opinion of the identity of the common Craw- 

 fordsville form with Lyon's species, described and figured what he took to be a variety of it 

 under the name Ta.vocrinus multibrachiatus var. collettl. He proposed his variety upon the 

 supposed fact that it had 5 primary radials (R + 4 IBr) in the anterior ray. This is not the 

 case, as his own figure shows — drawn by some one who did not understand the specimen ; 

 the fourth plate is the axillary, as appears beyond a doubt by the shape of the plate which is 

 angular above instead of having a concave waving suture line as all the non-axillary plates 

 have. The type specimen, formerly in the collection of Professor John Collett of the Indiana 

 Department of Geology, and supposed to have gone into the State Museum, cannot be located. 

 But the figure, though carelessly drawn and plainly incorrect in some details, shows a thor- 

 oughly characteristic specimen of this species, a little more elongate than the average 

 (PL LVI, fig. 1). The stem, with its abrupt change from the thin proximal columnals to 

 some other structure not well shown and probably not properly exposed in the specimen by 

 preparation, tells the story with absolute certainty ; and the usual pustulose ornamentation 

 is also present to reinforce the identification. So White really figured and described a per- 

 fectly normal specimen having the characteristic structure of the species, and it must there- 

 fore take his name in a full specific sense. But for this Quenstedt's figures, which are easily 

 recognizable, would have taken the species under T. meeki Quenstedt (not Hall). 



Miller and Gurley's T. splendens is founded upon an average specimen of the species, 

 with the characteristic stem and pustulose surface, as can be readily seen by comparing the 

 figures in Bulletin 8, Illinois State Museum, plate 5, figures 3, 4, with those on the two 

 plates herein. The authors in the same volume, page 8, expressly recognized White's variety 

 as a good species, but did not point out wherein their own differed from it, contenting them- 

 selves with their frequent conclusive declaration in such cases, that there is no described 

 species for which it can be mistaken, " by anyone competent to make a comparison." 



Ta.vocrinus collettl is a thoroughly well-marked species, standing between T. ungula 

 and T. praestaiis and perfectly distinguished from both, in addition to other characteristics, 

 by its remarkable stem. The peculiar and abrupt contraction, well illustrated by the figures, 

 is not known in any other crinoid except the little known " Ta.vocrinus" polydactylus of the 

 Irish Carboniferous, and it is constant for the species in both old and young. I have 60 

 specimens with this part of the stem attached, and there is among them not a single departure 

 from the rule. The change is Very sudden, not only in the diameter to the extent of about a 

 millimeter, but also from uniformly thin to alternating columnals ; the latter, however, is not 

 always observable on account of the peculiar surface markings ; the conical enlarged part is 

 also markedly shorter than in any other species. 



