CLEIOCRIXUS. 97 



nal specimens found by E. Billings there is also the crown which belongs 

 to the fragment figured by him as lc, which is very important, as it shows 

 most beautifully the real character of the arm structure. As these specimens 

 call for extended study and discussion, I will, to avoid frequent repetition, 

 designate them as follows: 



A. C. regius. Billings's principal type specimen, — original of Figs, la and 



16 of Plate V., Decade IV. A splendid specimen, much flattened 

 above the base, but otherwise beautifully preserved, with calyx com- 

 plete and perfectly exposed on both sides, and having small portions 

 of the column and arm bases attached. Billings's figure \<i shows 

 one side complete, but 16 gives the opposite view of the base only 

 (PI. I., Figs. 1 and 2). 



B. C. regius. Original of Billings's Fig. lc. Part of a column with two 



proximal rings of plates of the calyx attached (PI. I., Fig. 2>b). 



C. The remainder of the crown belonging to specimen B, not figured by 



Billings. Upper part of calyx and portion of arms and pinnules; — 

 greatly flattened, but very perfectly preserved on one side. The 

 fractured edge adjoining B is not quite perfect, some small pieces 

 being broken off (PI. I., Fig. 3a). 



D. Several pieces of column, nearly continuous from B, with terminal root, 



the original of Billings's fig. lg. Two of these are figured herein, 

 PL I., Figs. 3c and od, and the root, Fig. 3c. 



Specimens B, C and D are parts of the same individual, which 

 fit together very well, except at the junction of B and C, where 

 the edges of some plates are somewhat frayed by accident in col- 

 lecting ; and between 3d and 3c, where a piece is wanting. The 

 basal portion of the cabyx, 'being of very firm and rigid construc- 

 tion, was only slightly affected by pressure; but above, being 

 flexible and composed of thin plates, it was flattened out, so as to 

 become quite fragile in the fossil condition, resulting in the frac- 

 ture and loss of parts of some plates when exposed in the quarry 

 where it was found. 



E. C. magnificus. A very large crown, consisting of the calyx, with a very 



small portion of the stem, and the bases of part of the arms. The 

 surface of this specimen is very soft and friable, and it is considera- 

 bly injured. The preservation is quite different from that of those 



