FOSSILS OF THE NIAGARA GROUP. 359 



lying between tlie arm-bearing plates. The position of the aperture 

 has not been determined. 

 The specimen described has a length of one inch and a diameter of 

 five-eighths of an inch. 



Formation and Locality. — In the Racine limestone of the Niagara 

 group at Racine, Wisconsin. 



Among the collections from which the preceding species have been 

 described, there are some other obscure or imperfect fragments which 

 apparently belong to cystidean forms, but they are not in a condition to 

 be designated. 



These localities in Wisconsin have proved more prolific in species of 

 this family of fossils than any others known to me, and some of the 

 forms are m.ore remarkable than any heretofore described from rocks of 

 this age. In nearly every locality where these cystideans occur, the 

 Caryocrinus ornatiis has been found. The specimens, however, are for 

 the most part small or of medium size, and usually more elongated than the 

 same species in the Niagara group of New York or in Tennessee. 



GENUS GLYPTASTER, Hall. 

 Gltptaster occidentalis. Hall. 



PLATE X, FIG. 3. 

 Glyptaster occidentalis. Hall; m Transactions of the Albany Institute, IV, p. 204. 1862. 



The original specimens of this species were derived from the Niagara 

 shales and shaly limestones at Waldron, Indiana. Among the collections 

 from Racine, are some casts which are undistinguishable from those of 

 Waldron, and I have thus referred them. 



There are, however, some casts of a less rotund form, which is appa- 

 rently a distinct species. 



Glyptaster pentangularis, n. s. 



PLATE X, FIG. 4. 



Body reversed pyramidal, pentangular, regularly expanding to the bases 

 of the arms. Basal plates five, small; subradial plates short, show- 

 ing the commencement of ridges which unite on the first radial 

 plates. First and second radials marked by a central longitudinal 

 ridge, which divides on the third radial plate, as in other species of 

 the genus. Interradial spaces quite flat. 

 Cab. Nat. 47 



