104 
Kirtley F. Mather 
, Remarks. The genera Cromyocrinus and EupacJiycrinus are 
so closely related that they have sometimes been thought to be 
equivalent. The distinguishing characteristics are the small size 
of the infrabasal plates, which are commonly concealed by the 
column and are situated in a funnel-shaped cavity, of the latter 
genus in contrast to the larger infrabasals and convex or flat- 
tened base of Cromyocrinus. As thus distinguished Cromyo- 
crinus is represented by only three previously described Ameri- 
can species. These are C. globosus, C. hemisphericus , and C. 
papillatus, all described by Worthen from the Chester of Illi- 
nois. The type of the genus is C. simplex Trautschold from the 
Spirifer mosquensis zone of the Russian Carboniferous. The 
crinoid from the Coal Measures of Illinois described by Meek 
and Worthen as Cyathocrinus? sangamonensis has been re- 
ferred^^ to Cromyocrinus, but its true generic position is with 
Ulocrinus as it has only two azygous plates, the smaller one 
of which, the anal, rises partly above the level of the radials. 
Cromyocrinus therefore appears to be restricted, as far as 
it is known in North America, to the Chester and Pottsville 
stages of mid-Carboniferous times. Another undescribed spe- 
cies of the genus, much smaller than that now under discussion, 
has been recognized in a collection of fossils from the Wapa- 
nucka limestone which has recently come to hand. 
In comparison with other members of the genus C. grandis 
is distinguished primarily by its large size, none of the other 
species attaining much over one-half as great a diameter. The 
crater-like projection for the attachment of the stem, the marked 
constriction of the upper portion of the radials, and the close 
union of the infrabasal plates are also worthy of note. 
Horizon and locality. Brentwood limestone: near Brentwood, 
Arkansas (Station 145). 
Genus EUPACHYCRINUS Meek & Worthen 
Eupachycrinus cf. magister Miller & Gurley 
Plate II, figures 7-9. 
Numerous isolated basal and radial plates in several of the 
Morrow collections represent an Eupachycrinus which seems to 
closely resemble E. magister. The plates are covered with 
closely spaced, rounding tubercles irregularly scattered over the 
