FROM THE PALAEOZOIC ROCKS OF INDIANA, KENTUCKY AND OHIO. 



455 



ACTINOCRINUS MULTICORNUS, n. 8. 

 PI. XXVI, Fig. o. 



The body swells gradually from the arm-bases to the summit of the first radials; then 

 diminishes by_ a similar curve, to the bottom of the first radials; below this point the body 

 is unknown; the structure or arrangement of the species is nearly identical with A. penta- 

 spinus. The arm-bases are not quite so prominent as in that species. The first and second 

 radials, and the first interradials, are all spine-bearing. The spines on all the spine-bear- 

 ing pieces, are of equal size — short, stout, and pointed. The spines upon the first radials 

 rise less abruptly from the face of the piece than the others; the piece is also more gibbous 

 than the other spine-bearing pieces. 



The summit is crushed and the pieces disarranged. Among the disarranged pieces, 

 upon the summit, are some bearing strong spines ; nearly of the same form as the spines 

 upon the body. The arms are in groups of two for each ray — ten in all. Their form and 

 arrangement is unknown. 



The form is more delicate than A. pentaspinus, which it more nearly resembles than any 

 other known species. The points of the spines are not so acute as they are in that spe- 

 cies, and none of them are large or long. 



Size of Specimen. 



INCHES. 



Diameter of body to points of spines, ....... .80 



Height to top of arm-bases, 54 



Diameter of body, base of spines, 62 



Diameter across arm-bases, .60 



Locality. — Same as last. 



CYATIIOCRINUS. Miller, 1821. 



{Nat. Hist. Orinoidea.) 



CYATIIOCRINUS RARUS, n. S. 



PI. XXVII, Figs, i, i 1. 



Only two specimens of this unique species have been observed; both crushed, and the 

 parts thrown, more or less, out of their true relations to each other. The markings, or 

 ornament of the plates, are very prominent, giving a rough appearance to the body. Our 

 specimens show parts of three rays. The first ray-bearing pieces support, each, two free 

 rays ; these arc again divided on the second piece ascending. This arrangement gives 



