INVERTEBRATES. 313 



GENUS DICHOCKLNTJS, Munster. 

 DICHOCEINUS HAMILTONENSIS, Worthen. 



PL XXVII.. Fig. 10. 



Dichocrinus Hamiltonensis, WOETHEN, February, 1882. 

 Bulletin No. 1, of the Illinois State Museum of Natural History, p. 35. 



Body small, length and breadth apparently about equal, though 

 from the crushed condition of the body plates the exact proportions 

 of the body can not be accurately determined. Basals about half 

 as long as the radials, forming by themselves a low, shallow cup. 



Radials quadrangular, nearly once and a half as long as wide, 

 with a narrow, articulating scar at the summit for the reception of 

 the brachial series. 



Brachials three, the last one longer than those below, and sup- 

 porting on its upper sloping sides the first arm plates. 



Arms two to each ray, as far as can be seen in the specimen 

 before me, composed of short, wedge-shaped pieces, rounded ex- 

 teriorly, and giving off from their longest sides rather strong 

 pinnules. 



Column unknown. 



This species is nearly related to D. ficus, of Lyon and Casseday, 

 but differs from that in the shorter form of the body and in the 

 number of its brachial pieces, which in their species is only two to 

 each ray. 



Position and locality: Upper part of the Keokuk limestone, Ham- 

 ilton, 111. 



No. 267 of Mr. L. A Cox's collection. 



DICHOCEINUS COXANUS, Worthen. 



PI. XXVII, Fig. 7. 



Dichocrinus Coxanus, WOETHEN, February. 1882. 

 Bulletin No. 1 of the Illinois State Museum of Natural History, p. 35. 



Body small, ovate in outline, pointed at the base and contracted 

 at the summit of the radial series, so that its greatest diameter is 

 near the base of the radial plates. 



Basal plates nearly three-fourths as long as the radials, forming 

 by themselves a rather deep cup. 



