ae BNE oS ce eee , Aan ‘Si: = NIB SRN ae aN FS Sa PS 
= A a 4 : SWS gee =~ f= : ‘ Se : meee ; Be: ee 
' ~ — nn = a SS ee a SS se ee ee eee ee a 2 
ACTINOCRINID 2. 641 
rays. Arms comparatively short, and rather delicate; slightly flattened at 
the upper ends. Regular interbrachials: 1, 2, 2, followed by 2 and 1 plate 
within the rim; the latter piece arched over by the plates of the proximal 
pinnules of the proximal arms in adjoining rays; the anal interradius con- 
sists of 2, 3, 4, 2 and 2 plates. Interdistichals one, roofed by the incorpor- 
ated lower pinnules of the second arm. Tegmen rising but slightly at the 
top of the rim, the middle portion low dome shaped; the plates very 
numerous, irregularly arranged; nearly flat, gradually decreasing in size 
toward the arm bases. Anus subcentral, at the top of a small protuberance. 
Horizon and Locality. — Upper Burlington limestone ; Burlington, Iowa, 
and at several places in Missouri. 
Type in the (Worthen) Illinois State collection. 
ftemarks. — This species differs from the preceding one in the smaller 
size, the shortness of the calyx, the less number of arms, and in the convexity 
of the ventral disk. 
81 
