CRINOIDS AND BLASTOIDS. 197 



SUBORDER ARTICULATA. 



FAMILY ICHTHYOCRINID^. 



GENUS TAXOCRINUS. 

 TAXOCRINUS FLETCHERI Worthen. 



PL XV, Fig. 6. A specimen with arms and stem. 



PL XV, Fig. 9. Another specimen from the posterior side. 



1883, Worthen. GeoL Rep. Dlinois, VoL VH p. 308, PL XXX, fig. 2. 



Of about medium size ; rather short for its width ; arms stout, 

 short, closely folded together. The nature of the arms, and 

 still more the unusual size of the stem, gives to this species 

 that solid and robust aspect by which it is characterized, and 

 readily distinguished from all other species of this genus. The 

 specimens which we examined are all light in color. 



Underbasals entirely covered by the column, and also por- 

 tions of the basals. The exposed parts of the latter are penta- 

 gonal, twice as wide as high, obtusely angular above, except 

 the posterior plate which is slightly truncated. The basals, 

 together with the first and second primary radials, form a 

 conical cup with broadly truncate base. 



Primary radials three, transversely arranged, increasing in 

 width upward; their lines of articulation, like those of the 

 succeeding orders of radials and all arm-plates, strongly undu- 

 late, with short but wide patelloid pieces* interposed between 

 them. The first and second plates are about twice, and the 

 third three times as wide as high. The third radials, which 



*The patelloid pieces, although well defined in the specimens, were omitted in the 

 figures. 



