130 FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



Arms long and slender, composed of a double series of very narrow 

 short plates, interlocking on the back of the arm (which is there 

 slightly grooved) and angular on the edges. Each plate gives 

 support to a series of slender jointed tentacula, with a node or 

 short spine on the outer surface of each joint. 



Interradial spaces occupied by five, seven or more plates; the first 

 equal in size to the second radials, hexagonal, and supporting two 

 in the second series : two or three plates in the third and fourth 

 series. Intersupraradials two or three between the main divisions 

 of the ray. Anal area much larger than the interradial area, and 

 occupied by a greater number of plates in ranges of 1,3, 9, 5, 

 respectively; above which, they are irregularly placed. 



Surface of plates marked by a single set of rounded ridges, forming 

 pointed nodes in the centres; those traversing the radial series the 

 stronger and more elevated. Dome elevated; the plates bearing a 

 spine upon the centre of each. 



Geological formation and locality. In the shales of the Hamilton group: 

 Western New- York. C, A. White, collector. 



ACTINOCRINUS EUCHARIS (n.s.). 



Calyx somewhat larger than the medium size, broadly turbinate, a 

 little inflated in the lower part, with a thin trilobed rim at the 

 base of the cup, formed by the lower margin of the basal plates. 

 Easal plates low : first radials rather large, with large superior 

 lateral margins; second radials much smaller, hexagonal; third 

 radials less than two-thirds as large as the second, pentangular, 

 supporting on each of the upper sloping edges a primary supra- 

 radial of nearly equal size. These, on their outer sides, support a 

 series of three brachials, and on the inner a secondary supraradial : 

 this supports brachials on each of its upper faces, giving six 

 divisions to each ray before the arms become free ; while the cen- 

 tral branch of each main division again bifurcates after becoming 

 free, giving a formula of 



.8 



5 ^ — 40 arms. 



Interradial spaces large, occupied by ten or eleven plates each; 

 the first one equal in size to the second radial, hexagonal, and 

 supporting two smaller plates in the second range, one hexagonal 

 and one heptagonal, with three in the third range, two in the 

 fourth and fifth, and sometimes a small plate above. Intersupra- 

 radials three or more between the main divisions of the ray. 



Anal area much larger than the interradial area, and occupied by 



