650 THE CRINOIDEA CAMEEATA OF NORTH AMERICA. 



were enabled, through the liberality of our American Museums and collec- 

 tors, to make direct comparison with the types of almost every species, 

 except some of those described by S. A. Miller, and Hall's Richfield speci- 

 mens in the New York State Cabinet. 



The eleven groups into which we arrange the species are based variously 

 upon the style of ornamentation, the general form of the calyx, the details 

 of the arm structure, and other characters, none of which can be regarded as 

 of generic importance. Some of these groups are apparently unrepresented 

 in Europe. None of the European species known to us are referable to the 

 Discoideus group, nor to the Subspinulosus, Sarse, or Truncatulus groups. 

 The European species, as a rule, are coarser in their ornamentation, the 

 slope of the cup more abrupt, the plates heavier, the suture lines and rugosi- 

 ties of the plates deeper, the nodes stronger, the ventral disk higher, and 

 often surmounted by a large anal tube, somewhat resembling that of 

 Actinocrinus and Bcdocrinus. The facets upon the radials also, as a rule, 

 are deeper, and are frequently provided with a transverse ridge, mdicating 

 that the union with the brachials was not very rigid. 



We have rejected the following species as unrecognizable on account of 

 insufficient preservation, or inadequate description. 



p. ahsentimis S. A. Miller, Cliouteau group, Sedalia, Mo. 



P. amabilis S. A. Miller, Burliugton group (?), Loc. (?). 



P. annosus S. A. Miller, Chouteau group, Sedalia, Mo. 



P. altidorsatus Rowley and Hare, Upper Burlington limestone, Louisiana, Mo. 



P. bcdfordensis Hall and White., Waverly group, Bedford, Ohio. 



P. Blairi S. A. Miller, Burlington group, Sedalia, Mo. 



P. calj/C2dus Hall, Burlington group, Burlington, Iowa. 



P. chouteaueiisis S. A. Miller, Chouteau group, Sedalia, Mo. 



P. Colletli S. A. Miller, Chouteau group, Sedalia, Mo. 



P. cQimnnus S. A. Miller, Burlington group, Sedalia. 



P. ehoraceus Hall, Hamilton group, Livingston Co., N. Y. 



P. Baijdeni Meek, Subcavboniferous, Montana. 



P. marginatus RowL. and Hare, Upper Burlington group, Pike Co., Mo. 



P. pentagonus S. A. Miller, Keokuk group, Boonville, Mo. 



P. plano-basalis RowL. and Hake, Upper Burlington limestone, near Curryville, Mo. 



P. pmnilus Hall, "Warsaw limestone, Warsaw, Bis. 



P. vexabilis White, Subcarboniferous, Nevada. 



The following species we consider to be synonyms: — 



P. iBteriialis S. A. Miller = P. bonoensis White. 



P. ttlabamemis S. A. Miller = P. Bmtsmllie Troost. 



P. batiola S. A. Miller = P. aqnalis Hall. 



P. bloomfieldemis S. A. Miller = P. planus 0. and Shum 



P. BroadJieadi S. A. Miller := P. americatms 0. and Sh. 



P. cadncus S. A. Miller = P. bonoensis White. 



P. carcliesium S. A. Miller = P. pileiformis Hall. 



