30 PROCEEDINGS OF THE AMERICAN ACADEMY 



i"ays have three, and then the number is twelve. In some specimens, 

 the ray to the left of the anal field supports four arms, and that on the 

 right of it three ; when this is the case, the arms are thirteen in num- 

 ber. The arm facet is large and nearly circular, and, as before stated, 

 deeply grooved in the upper part ; the piece of the vault which rests 

 upon the arm pieces is also indented, the opening into the body 

 being partly in these and partly in the arm pieces. The last pieces 

 of the secondary radials form a closed ring around the calyx, except 

 on the anal side. 



Inter-radial pieces four, one to each field ; they are the largest 

 pieces forming the calyx, longer than wide, septagonal or hexago- 

 nal ; they rise between the first radials, and reach the last secondary 

 radials. 



Anal pieces usually four ; the first is hexagonal and rests on the 

 basal pieces, its summit is truncated and supports the fourth anal 

 piece, its oblique margins support two pieces, one on either side, nearly 

 equal in size, pentagonal or obscurely hexagonal : the fourth piece is 

 long, lanceolate, and extends between the pieces which support the 

 arms, reaching to the vault. 



Vault. The vault or summit is covered by rather large, polygo- 

 nal pieces, interspersed amongst which are a few qiiite small ones. 

 All the pieces covering the vault are prominent, and inflated in the 

 centre. 



Moutli nearly central. The form of the proboscis is unknown ; it is 

 broken from all the specimens which liave come under our observa- 

 tion. The whole character of this species is coarse and robust. 



Column. Unknown. 



The calyx is covered by minute granular markings. 



Dimensions : — 



Height of calyx . . . . . . .10 inch. 



Greatest diameter of calyx . . . . . 1.25 " 



Height of specimen . . . . . . 1.05 " 



Diameter of joined basal pieces .... .25 " 



Diameter of arm facets ..... .25 " 



Geological position and locality. Rather abundant in sandy mud- 

 beds at the top of the Knob-member of the subcarboniferous limestone, 

 Clear Creek, Hardin County ; also near Scottville, Allen County, Ken- 

 tucky, &c. 



