PALAEONTOLOGY OF IOWA. 583 



single or double series radiating from the centre to the sides 

 of the plate ; the intermediate spaces strongly granulose, or 

 fine tuberculous. Column and arms beyond the bases un- 

 known. 



This species is referable to a group of Actinocrinides, among which A. costatus, 

 Jl.polydactylus, A. icosidactylus, and others, may be arranged. Although approaching 

 some European forms, the species under consideration is not so closely allied as to 

 require the distinctions to be pointed out. 



Fig. 11 a. View of specimen, looking upon the postero-lateral ray, the anal 

 side being upon the right. 



Fig. 11 b. Anterior side of specimen. 



Geological formation and locality. In the Burlington limestone : Bur- 

 lington, Iowa. 



Actinocrinus ornatus ( n. s.). 



PLATE X. FIG. 12. 



BODY broadly turbinate : dome a little elevated above the 

 arm-bases : base truncate ; the margins of the basal plates 

 extended below the point of attachment, and surrounding 

 the summit of the column in a subdenticulate outline. Radial 

 plates wider than long. Second radials hexagonal. Third 

 radials equal to or larger than the second radials, octagonal, 

 supporting on each upper oblique side a subhexagonal supra- 

 radial plate ; and each of these, two other plates, the outer 

 ones of which are brachial plates, being truncate and sup- 

 porting a single second brachial plate ; while the inner ones 

 are obtusely wedgeform above, supporting on one side a bra- 

 chial plate and on the other a third supraradial ; giving four 

 brachial plates and as many arms from each first supraradial, 

 or eight arms from each ray, the supraradial plates being 

 separated by two intersupraradial plates. First interradial 

 plate a little larger than the second radials ; a second and 

 third range of two each, hexagonal or pentagonal, the third 

 series supporting one or two small plates between the arms. 

 Anal plates somewhat smaller and shorter than the radials, 

 making that side of the calyx shorter than the other. 



