11 



each upper sloping side a single secondary radial. The second- 

 ary radials are quite small and thin, and each one bears three 

 or more short tertiary radials before the arms become free. 

 Most of the arms bifurcate almost immediately^ after becoming 

 free, and again at irregular distances from the calyx. The ray 

 on the left of the specimen illustrated preserves nine arms near 

 the calyx, and probably the lower one bifurcated at the place 

 at which it is broken off, and two of the arms are preserved 

 above another division. The ray on the right of tlie illu.stra- 

 tiou, though not so well preserved, appears to have had the 

 same number of arms. The central ray, however, appears to 

 have had only six arms, near the calyx, and only one of these 

 is preserved far enough to show a second bifurcation. The 

 probability is that a complete specimen would have from forty- 

 six to fifty arms, near the calyx, and a number of bifurcations 

 above. The arms are exceedingly long and of uniform size, each 

 branch being about as large as the ai'ui below the bifurcation. 

 They are composed of a double series of very short interlocking 

 plates bearing dense pinnules. 



First regular interradial hexagonal smaller than a second 

 primary radial, followed by two smaller plates in the second 

 series, and three smaller ones in the third, that unite with the 

 plated of the vault. Surface of the interradials ornamented 

 the same as the second and third primary radials. Azygous 

 plates unknown. 



This species is remarkable in the number and structure of the 

 arms, and the surface ornamenta.tion of the calyx will also serve 

 to distinguish it. Possibly this species belongs to Eretmocrinus, 

 though the arms are those of Actinocrinus. 



Named in honor of William Gibson, of Belpre, Kansas, to 

 whom science is indebted for the discovery of many interesting 

 fossils. 



Found in the Keokuk Group, on Indian creek, near Crawfords- 

 ville, Indiana, and now in the collection of Wm. F. E. Gurley. 



ACTINOCRINUS AUGU8TATUS, U. Sp. 



Flate XII, Figs. 8 ana 8a, Vol. VIII, Geo. Sur. 111., and described 

 on page 97 of the same volume, as Actinocrinus lobatus. Hall. 

 Body large. Calyx somewhat obpyramidal, longer than wide; 



radial ridges moderately protuberant; interradial areas small, 



