Il6 SMITHSONIAN INSTITUTION 



PLATE LV 

 (All figures natural size) 



PAGE 



Figs. l-io. Taxocrinus ungula Miller and Gurley 397 



Fig. I. The type, showing the characteristic claw-like aspect of the rays; posterior view. Uni- 

 versity of Chicago. 

 2, 3, 4. A series of perfect, mature crowns, all more or less flattened, posterior view ; showing 

 the prominent and claw-like rays, anal and iBr structures, and the uniformly 3 IIBr. 



5. Anterior view of a similar specimen, with stem attached ; showing the arrangement of 



iBr plates to the third order, and the stem characters. Infolding distal ends of arms 

 shown above iBr. 



6. A large crown, with less conspicuous change in the arms above the IIIBr. 



7. A more elongate variation of the species ; it has 4 IIBr in two rami not shown in the 



figure. 

 ■ 8a, b, ga. Characteristic young specimens, but little flattened, from the same colony as the 



preceding; showing small development of iBr; fig. 8 has 2 or 3, and fig. 9 only i. 

 gb. R. ant. interradius, showing only i plate. 



10. Young specimen with more elongate habitus than the others, having 4 IIBr in the anterior 



ray. 



11. A very young specimen of Taxocrinus colletti, with.no iBr at all, showing the contrast in 



contour with T. ungula, even at this young stage. 



Keokuk Or. ; Lower Carboniferous. Indian Creek, Indiana. 



All specimens figured on this plate, except that of fig. i, are in the author's collection. 



