ARCHAEOCIDARIS. 267 



'Archaeocidaris coloradensis nom. nov. 

 Plate 13, fig. 6. 



Archacocidaris ornatus Newberry, 1861, p. 116, Plate 1, figs. 2, 3, 3a; Keyes, 1895, p. 191 ; Klem, 1904, p. 54 

 (non Echinocrinus [Archaeocidaris] ornatus Eichwald, 1860, p. 654, Plate 32, fig. 24; non Archaeoci- 

 daris ornatus White, 1877, p. 104, Plate 6, fig. 7a, White's figure is here referred to A. mucronata, p. 271). 



Archaeocidaris ornata Loven, 1874, p. 44; Lambert and ThieVy, 1910, p. 124. 



Known only from fragmentary primary spines. These are 2.5 inches long by 0.36 of an 

 inch in diameter, according to Newberry, but it may be remarked that his figured specimens 

 are much shorter and very fragmentary. The spines are thickly studded with short spinules 

 irregularly arranged, with points directed slightly distally. As Newberry's name ornatus 

 is preoccupied by Eichwald 's ornatus (see p. 274), I give a new name to the species. 



Carboniferous (Coal Measures), Crinoidal Limestone, near junction of the two Colorados, 

 and in same horizon, 60 miles west of that point, near Great Canon of Colorado. Cotype 

 (Plate 13, fig. 6), Columbia University Collection, no. 6,900 G. 



* Archaeocidaris keokuk Hall. 

 Plate 13, figs. 7a, 7b. 



Archacocidaris keokuk Hall, 1858, p. 699, Plate 26, figs. 2a, 2b; Keyes, 1894, p. 128; Klem, 1904, p. 50. 

 Archaeocidaris wortheni Zittel, 1879, p. 485, text-fig. 343d (not 343a-343c, which are true worthrni). 

 Archaeocidaris keokuk (Heterocidaris) Lambert and Thiery, 1910, p. 124 (their page and plate references 

 are to true A. keokuk, but this is not Helerocidaris keokuk, see Nomina Nuda. 



Fragmentary known. Interambulacral plates low, wide hexagons, basal terrace marked, 

 scrobicule wide, secondary tubercles on narrow rim around the margin. Spines circular in 

 section, of moderate length, muricate, with elongate ridges and spiniform tubercles. 



Keokuk Limestone, Lower Carboniferous, Warsaw, Illinois, American Museum of Natural 

 History; Clark County, Missouri; Boonville, Missouri (Klem). 



*Archaeocidaris gracilis Newberry. 

 Plate 13, fig. 8. 



Archaeocidaris gracilis Newberry, 1861, p. 117, Plate 1, figs. 4, 4a; Klem, 1904, p. 49; Lambert and Thit'ry, 

 1910, p. 124. 



Fragmentarily known. Newberry says that the form of the interambulacral plates is 

 unknown, but a fragment shows a single row of secondary tubercles around the scrobicule. 

 Primary spines straight or curved, slender, tapering, circular in section, surface set with small 

 spinules pointing distally. 



