OWEN AND SHUMARD'S FOSSIL CRINOIDEA. 69 



First series of perisomic plates six, large, moderately convex ; five are hexagonal, 

 and one pentagonal. These pieces are bent inwards and slightly upwards near their 

 inferior margins, and project below the plane of the basal plate, which is not visible 

 when a side view of the fossil is taken. The second series consists of thirteen 

 hexagonal plates, somewhat smaller than those of the first series. On these rest the 

 third series composed of nineteen pieces, eight are hexagonal, six are heptagonal, and 

 five are pentagonal. These again are surmounted by six ranges of polygonal plates, 

 the plates of each range becoming successively smaller and more numerous as they 

 approach towards the summit of the cup. All the plates which go to form the sides 

 of the body are smooth and slightly convex on the surface. 



The coronal integument is slightly elevated and composed of innumerable little 

 polygonal plates, some are larger than others, and these are mamillated in their 

 centres. 



The proboscis is situated on the side of the cup a little below its superior margin. 

 A small portion only remains attached in our specimen. It was evidently short and 

 slender. 



Column and arms unknown. 



Dimensions. — Height 25 lines, width at summit 32 lines, do. at base 13 lines, 

 diameter of basal plate 7 lines. 



Formation and Locality. — It occurs with the preceding species in the sub- 

 carboniferous limestone at Burlington, Iowa. For the magnificent specimen figured 

 we are indebted to Mr. John Evans, of the U. S. Geological Corps, and to him we 

 have dedicated it. 



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