DESCRIPTIONS OF SPECIES. 331 



A single specimen, not very perfect, which resembles A. tnidifer closer than 

 any described species except, perhaps, A. edgarensis. The figures of these two 

 species are so similar as to suggest that both names were proposed for the same 

 specific type. 



Locality. — Leadville district (station 2265). 



Arch^ocidaris ohnata Newberry. 



1861. Archxocidans omatus. Newberry, Ives's Colorado Kiver Expl. Exped., p. 116, pi. 1, figs. 2. 3, 3a. 



Upper Carboniferous limestone: Banks of Colorado River. 

 1877. Archxoddaris omaius. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 104, pi. 6, 

 fig. 7. 



Carboniferous: Ojo del Oso, near Fort Wingate, N. Mex. 

 1895. Archieocidaris omatus. Keyes, Iowa Acad. Sci., Proc, vol. 2, p. 191. 



Carboniferous: Ojo del Oso, N. Mex. 



One good specimen from the San Juan region (station 2235) is clearly the form 

 which White identified with Newberry's species. At the two other localities the 

 material is too imperfect to admit of a conclusive identification. 



Locality and horizon. — San Juan region (station 2235); middle portion of Her- 

 mosa formation. Leadville district (stations 2265, 2267) ; base of the Weber formation. 



ARCELffiOCIDARIS GRATIS White. 



1876. Archieocidari.i oralis. White, Powell's Rept. Geol. Uinta Mountains, p. 109. 



Lower Aubrey group: Confluence of Grand and Green livers, Utah. 

 1880. Archseocidaris craiis. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

 p. 1.30, pi. 33, fig. 2a. 



Middle Carboniferous: Confluence of Grand and Green rivers, Utah. 

 1895. Archseocidaris crads. Keyes, Iowa Acad. Sci., Proc, vol. 2, p. 188. 



Coal Measures (Lower Aubrey) : Utah. 



This species is abundant near Ouray (station 2195b) and in fair preservation. • 

 Fragments of what is doubtless the same form were collected in the Leadville region 

 (station 2265) and in the Crested Butte region (station 2307). This species is related 

 to one described and figured b}' Keyes" as A. megastyhts Shumard, and it would be 

 little surprising if the one form should be traced into the other. The interambulacral 

 plates have almost precisely the same characters in both, but the spines of A. mega- 

 stylus are much larger and less spinose than the type known as ^1. cratis. It should 

 be noted, however, that in the latter species the large spines or portions of spines 

 have fewer subsidiarj^ spinules than the smaller ones or portions. 



Locality and horizon. — Crested Butte district (station 2307); Weber limestone. 

 Leadville district (station 2265). Ouray (station 2195a); Hermosa formation. 



"Missouri Geol. Surv., vol. 4, 1894, p. 129, pi. 15, fig«. 2(i. 26. 



