356 SMITHSONIAN INSTITUTION 



cirri prominent at distal end, sometimes extending with a semblance of regu- 

 larity half way up the column. 



This is a closely similar species' to G. expansus, but of a more slender habitus. It is the 

 first occurrence of the genus recorded from America, and the material for illustrating it is 

 unusually good, including various stages of growth from mature to very young, where the 

 arms infold at the IIBr (PI. XLVII, fig. 12). In this specimen, which has a complete stem, 

 the great length of the columnals in the young is well shown, as compared with those of the 

 adult stem in figure 7. 



Type. Author's collection. 



Horizon and locality. Silurian, Upper Niagaran Group, Brownsport limestone, Beech 

 River formation; Decaturville, Decatur County, Tennessee. 



Gnorimocrinus varians n. sp. 



Plate XLVII, figs. 13-17 



Perhaps only a variant of G. cirrifer with which it is associated in the same 



bed ; but it is distinguished by its more tapering, slender arms, relatively large 



size of RR, and greater difference between them and the succeeding IBr, giving 



more the appearance of a defined calyx; also by the tendency to reduction in 



number of IIBr, which in one out of five specimens are 2 all around, and partly 



so in two. This form is a variation in the direction of the large species from the 



same formation which has been placed under the Lecanocrinidae as a new 



genus, Asaphocrinus, in some ways closely related to Gnorimocrinus , and some 



of the specimens of the present form may possibly be younger stages of that 



species. 



Types. Author's collection. 



Horizon and locality. . Silurian, Upper Niagaran, Brownsport limestone, Beech River 

 formation ; Decaturville, Decatur County, Tennessee. 



