37 



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

 each upper sloping side a free arm giving to the species ten 

 arms. The arms are long subfusiform, and composed of a 

 single series of short plates with transverse sutures above 

 the first plate. 



Azygous plates three. The first one is subquadrate, except 

 being slightly truncated at one angle by the third plate, it, 

 therefore, has five sides. It is not as large as a first radial 

 and rests between the superior sides of two subradials and 

 below the first radial on the right and supports on its two 

 upper sides the second and third azygous plates. 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 the right. 



This species is distinguished by its general form, small 

 basals and azygous plates. 



Pound by the late Wm, McAdams, in the Kaskaskia Group, 

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

 F. E. Gurley, 



Family RHODOCRINID^E. 



RHODOCR1NUS BLAIRI, n. Sp. 



Plate II, Fig. 20, basal view; Fig. 21, azygous side; Fig. 22, 

 opposite side; Fig. 23, summit view. Each of these 

 views is magnified two diameters, and they 

 are all taken from the same specimen. 



Species 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 largest plates in the 

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

 heptagonal. They are abruptly bent and rounded in the mid- 

 dle, the lower part forming part of the funnel-shaped columnar 

 civity and the upper part curving as abruptly upward. First 

 primary radials about half or two- thirds as large as the sub- 

 radials, two hexagonal and three heptagonal. Second primary 



