FOSSILS OF THE CARBONIFEROUS. 
A list of all the species known to occur in the Carboniferous formation 
of the Eureka District is given in the systematic catalogue at the end of 
this report, and only the rarer forms and new species are mentioned in 
the text. In some instances a species is partially identified by fragments, 
in which case the similarity to the described species is mentioned in the cat- 
alogue. 
ECHINODERMATA. 
Of this class, representatives of the Echinidea were obtained in the 
spines of two species, and of the Crinoidea in numerous segments of the 
columns of several species. As a whole the class is very imperfectly repre- 
sented in the central portions of the Rocky Mountain area, and with the ex- 
ception of a few species from Montana and New Mexico the great Crinoidal 
fauna of the Lower Carboniferous limestones of the Mississippi Valley is 
unknown in the Rocky Mountains. A further examination of the Lake 
Valley District in New Mexico, however, will undoubtedly add largely to 
the knowledge of the distribution of the Crinoidal fauna, as several species 
from there are identical with those from the Burlington limestone. 
Since the above was written Mr. F. Springer (Amer. Jour. Sci., vol. xxvii, 
p. 97, 1883), has described a large and varied fauna from the Lake Valley 
District. 
Genus ARCHASOCIDARIS McCoy. 
Archeocidaris, sp.? 
Two species are represented by the spines. One is very much like A. 
Wortheni Hall (Geol. Surv. Iowa, vol. i, pt. 2, p. 700, 1858), and the other 
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