562 KANSAS CITY REVIEW OF SCIENCE. 



numbers of these animals were destroyed in this way, and that the crinoids did 

 not subsist upon " minnows, or star-fishes, or moUusks that happened to come 

 in their way." Indeed, we must confess that after years of vejy careful observa- 

 tion we have never yet found a specimen which furnished satisfactory evidence 

 as to what the crinoid subsisted upon. 



To the head of the crinoid was attached an appendage, which, for want of a 

 better name, we call a stem. This is composed of a series of fiat calcareous 

 rings or plates, perforated at the center. The reader will recognize in these 

 plates the Pulley-stones, and St. Cuthbert's Beads already alluded to. The broad 

 surfaces of these rings, in the larger species especially, are striated from the cen- 

 tral perforation to the circumference. As the surface of the plates enlarges to- 

 wards the circumference the striae bifurcate to keep the intervening spaces all 

 equal. These plates are laid one upon another, the surfaces being so arranged 

 that the striations of the one fit exactly into the little grooves of the other, the 

 sutures around the margins having the appearance of saw-teeth fitted together. 

 By this means the possibility of any rotary movement of the plates upon each 

 other seems to have been effectually prevented. This, however, did not prevent 

 considerable flexibility in the stem, as in the case of the Goniasteroidocririus 

 already alluded to. 



So great is the diversity in the exteral margins of these rings, that it is easy to 

 distinguish many species by the appearance of the stems. We feel satisfied that^ 

 before a complete and satisfactory classification of these animals can be made, 

 these stems will need to be more thoroughly studied. Endless variety would 

 seem to be the design of nature in the construction of these stems as in the other 

 parts of these animals. And equally interesting is the study of the different con- 

 struction and markings of this singular appendage. 



The growth of the stem seems to have been by successive additions of new 

 plates at the junction with the base of the head. In most species these at first 

 are quite thin, but they increase in thickness as the formation of new plates 

 removed the older ones farther and farther from the point of origin. By this 

 double process, no doubt, the stems were lengthened. These plates were doubt- 

 less held together by muscular attachments, and the cavity within filled with 

 animal substance. 



Everything seems to indicate that these stems, and the arms as well, were 

 exceedingly fragile, and on this account, it is very difficult to obtain an entire 

 crinoid, or even a head with a long piece of stem attached. No doubt many 

 suppose this is owing to the difficulty of removing the specimens from the quarry- 

 without breaking, but such is not the case. The fact is, the crinoids were broken 

 before they were fossiHzed, even while yet alive. In the large slab already 

 alluded to, containing eighty crinoids, not more than half a dozen were entire, 

 and these were mostly young specimens, or small species. The stems were 

 nearly all broken, having been slipped apart at the joints, leaving stumps of 

 various lengths attached to heads. In removing the matrix from specimens in 

 these large slabs, I have repeatedly found the stems diisj.ointed by too^ sliort a 



