OBINOIDS. 161 



cies bave no analogies among the recent forms. These and 

 otlier discoveries have necessitated a complete recasting of 

 the whole systematic arrangement of the class. In the main, 

 however, the ordinal limits probably coincide closely with the 

 groups lately outlined by Wachsmuth & Springer, the leading 

 authorities on this class. 



The Crinoidea now appear to fall naturally into four grand 

 divisions : ( 1 ) the Camerata, ( 2 ) the Inadunata, ( 3 ) the Artic- 

 ulata, and (4) the Caualiculata. The first of these sections is 

 characterized by forms having relatively large, more or less 

 globular calyces, near the equatorial zone of which the free 

 arms are given off; by having comparatively short arms; by 

 the presence of a greater or less number of interradials ; and 

 by the loss of pentamerous symmetry through the intercala- 

 tion of plates on the posterior side. The ventral surface is 

 often produced into a long anal tube, which usually extends 

 beyond the ends of the arms. 



The Camerata are almost exclusively Paleozoic forms. In 

 sculpturing great diversity is presented, such as is nowhere 

 else found among the feather-stars. Some species have per- 

 fectly plain surfaces ; others are slightly ridged or corrugated. 

 Many exhibit solitary nodes and simple ridges ; closely related 

 forms, rough, monstrous tubercles and bold, massive folds. A 

 few have quaint, unique designs ; while several small groups 

 present straight, angular patterns. Still others show delicate, 

 subdued styles of ornamentation and flowing traceries, com- 

 plex and intricate. These characters, together with the numer- 

 ous gracefully curved arms, fringed on either side with long, 

 slender pinnules, and the curious flexible, knotted stems, cer- 

 tainly make the " stone-lilies " very attractive to scientist and 

 layman alike. 



The Inadunata embrace some of the most interesting 

 forms of the brachiate echinoderms: those in all essential 

 respects larval, and those closely resembling the later seden- 

 tary species. Simplicity of structure everywhere prevails, 

 whether in the low calyx or in the long, uniserial arms. A 

 very marked contrast do they present to the members of the 



