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series, and is strongly elevated on the brachial plates. 

 The other plates are destitute of markings except a finely 

 granulose structure. 



This species has some resemblance to Actinocrinus (Sac- 

 cocrinus) speciosus (Pal. N. F., vol. II, p. 205, pi. 46, fig. 1), 

 but it differs in the proportional size and form of plates, 

 in the ridges of the radial series, and in having a second 

 bifurcation of the rays previous to their separation from 

 the body. 



Geological formation and locality. — In shales of the age of 

 the Niagara group j Waldron, Indiana. 



GENUS EUCALYPTOCRINUS (Goldfuss). 



EUCALYPTOCRINUS CRASSUS (Hall). 



Body massive, turbinate from the base to the arms, and 

 with the interbrachial plates and arms attached, it has a 

 general subovate form, with a truncate base, which in 

 most specimens is deeply impressed. Basal plates small ; 

 concealed by the basal cavity. First radial plates much 

 larger than the succeeding ones, height and width sub- 

 equal. Second radials quadrangular, length and breadth 

 equal, the greatest width at the base. Third radials hex- 

 agonal, the lower lateral, and upper sides shorter than the 

 other three. First supraradiais somewhat smaller than 

 the third radials, pentangular in well formed specimens. 

 Second supraradiais less than half as large as the first, 

 pentangular, supporting on each upper sloping side a small 

 triangular plate, upon which rests the first arm plates. The 

 interradial plates are one large and two smaller, to each 

 field ; the large one is ten sided and elongate-ovate, the 

 greatest width above the middle ; the others are nearly as 

 long, but narrow, united by their inner margins the entire 

 length, their greatest width below the middle ; their sum- 

 mits reach as high as the fourth or fifth pair of arm 

 plates. The intersupraradial plate is single, having the 

 [Trans, iv.] 27 



