tracted on tlie sides. Each one is axillary and supports on 

 each u])per sloping side a free arm ijiving to tlu; s])ecies ton 

 arms. The arms are lon<^ subfusiform, and C(>m])osod of a 

 sinii'lf series of short ]>Uites with transverse; siitui'cs aho\'t' 

 the tirst plate. 



Azyecous ])la.tes three. The tii'st one is suljqvuidrate. exee])t 

 beini? slig'htly truncated at one ani;'le by the third plat(\ it, 

 therefore, has live sides. It is not as large as a first i-a.dial 

 and rests between the su])ei-ior sides of two subradials and 

 below the first radial on the riirh^' and supi)orts on its two 

 ui>per sides the second and thii-d azygous ))lates. The second 

 azygous plate is smaller than the first, truncates a subradial 

 and abuts a first radial on the left. The third azygous plate 

 is smaller than the second, truncates the first and separates 

 the second from the first radial on tlie right. 



This species is distinguished by its general torn), small 

 basals and azygous plates. 



Pound by the late Wni. McAdams, in the Kaskaskia (iroup, 

 Randolph county, Illinois, and now in the collection of Wm. 

 F. E. (iurley. 



Family RHODOCRINID.F.. 



UHODOt'lJlNrS RT.AIUI. n. S]). 



Plnle II, Fig. 20, hasal ricw: Fig. ?/, azygous side; Fig. 22, 



opposite side: Fig. ,?•>, siimmH rieir. Eavh of ihcse 



vieirs is magnified Iwo diavieiers, and iheij 



are all ial<en from ihe same specimen. 



Sjiecies small, much below medium size. Calyx bowl-.shaped, 

 subpentagonal in transverse section; radial ridges moderately 

 well defined; plates convex. Basal cavity very deep. Column 

 small, canal minute. 



Basals form a cone within the calyx, into which the end of 

 the column is inserted. Subradials the larg(\st plates in the 

 body, very convex, as long as wide, one octagonal, the others 

 heptagonal. They are abru])tly bent aii<l rounded in the mid 

 dl(!, tlio lower pai't forming i)art of the funiKd shaped columnar 

 civity and the upi)er part curving as abruptly ujiward. First 

 pi'iuiai-y radials about half or two-thirds as hirge as the sub- 

 radials, two hexagonal and three he])tagonai. Second jii-iuiarj' 



