AHCHAEOCIDARIS. 261 



There are four columns of plates in each interambulacrum; these plates arc low. wioV h \:gons, 

 the basal terrace is clearly marked in the scrobicular area (Plate 8, fig. 7). Spines arc -month, 

 tapering, slightly arcuate. Secondary spines are on the borders of plates associated with 

 secondary tubercles (Plate 9, fig. 13). 



The type of A. legrandensis (Plate 10, fig. 4) is a very small and not well pre-crvcd speci- 

 men, but it has low hexagonal plates and smooth, slightly arcuate spines. AH I cannot dis- 

 tinguish this species from blairi, therefore legrandensis, which is the older name, has priority. 

 Miller was mistaken in referring blairi to the genus Eocidaris, for since the basal terrace is 

 perfectly clearly marked, this feature indicates that it is an Archaeocidaris. 



The type specimen of legrandensis is from the Kinderhook Group, Ixtwer Carboniferous, 

 Le Grand, Iowa, now in Chicago University Collection 6,198. A second specimen from the 

 same locality and collection is no. 12,314. The specimens originally described as Eocidari* 

 blairi, here considered a synonym, are from the Keokuk Group of Boonville, Missouri, now in 

 Chicago University Collection 8,855. Keokuk Group, Canton, Indiana, a ventral view, with 

 some spines in place, Museum of Comparative Zoology 3,198; Keokuk Group, Bono, Lawrence 

 County, Indiana, Museum of Comparative Zoology, two good specimens, one (3,199) showing 

 four columns of plates in each interambulacral area and the other (3,200) spines in place. In the 

 Springer Collection a specimen 8,024, from the Kaskaskia Group, Pulaski County, Kentucky, 

 and one 8,083, from the Keokuk Limestone of Bono, Indiana, are referred to this species. 



* Archaeocidaris longispina Newbt-rry. 

 Plate 10, fig. 1. 



Archaeocidaris longispina Newberry, 1861, p. 116, Plate 1, figs. 1, la; Keyes, 1895, p. 191; Klein, 1904, 



p. 51 ; Lambert and Thiery, 1910, p. 124. 



Known only from primary spines which are long, smooth, narrow above the milled ring, 

 inflated in the lower half and thence tapering to a point, Newberry says 2.5 to 3.5 inche- in 

 length. The longest of the three type specimens measures 63 mm. in length and 6 mm. in 

 diameter at the widest part. 



Crinoidal Limestone, upper part of Carboniferous (Coal Measures), on the banks of the 

 Colorado River. The type consists of three spines on one slab. It is in Columbia University 

 Collection 6,419 G, and bears the label "Coal measure limestone, North Arizona." 



*Archaeocidaris glabrispina (Phillips). 

 Plate 10, figs. 2a-2b, 8a-8e, 9. 



Cidaris glabrispina Phillips, 1836, p. 208. 



(?) Echinocrinus glabrispina M'Coy, 1844, p. 173. 



Archaeocidaris stellifera Daily, 1877, p. 18, text-figs, a-e. 



