474 THE CEINOIDEA CAMERATA OF NORTH AMERICA. 



the radials; wider than high, and spreading but httle at the sides. PLates 

 moderately convex, without ornamentation ; suture lines well defined, with a 

 small pit at each angle of the plates. Color of specimens as in A. inimaiiirus. 



Basals forming a disk, which rests within a shallow concavity formed by 

 the united radials, and not visible in a side view. Eadials large, heptagonal, 

 narrow below and wide above, the lower end curving in^Yard. Costals small, 

 nearly of equal size. Distichals unevenly distributed among the rays, the 

 three anterior rays having from two to three in the calyx, which are fol- 

 lowed by free arm plates ; the two posterior rays, in the division next to 

 the anal side, but one, which is axillary and followed by two fixed palmars ; 

 the opposite side having three distichals, thus making fourteen arms to the 

 species. Arms arranged in groups, the space between the posterior rays 

 much the widest; they are quite robust, tapering at the end, rounded, and 

 biserial except one or two cuneate pieces at the base. Interbrachials in two 

 ranges; the first very large, reaching the top of the costals, and touching the 

 distichals, the others small, resting between the distichals. A third range is 

 on a level with the arm bases, and followed in four of the areas by four to 

 five interambulacrals. Anal area very wide, elevated along the median line, 

 deeply grooved at each side, so as to form from the distichals to the posterior 

 oral a longitudinal ridge, which is most prominent in the upper part around 

 the anus. First anal plate larger than the radials, longer than wide ; the 

 second, and the interbrachials at the sides, as large as the corresponding 

 single plate of the other areas ; the plates above small and irregular in 

 their arrangement. Tegmen depressed convex. Orals large ; the posterior 

 one extended into a thick, elongate node, and twice as large as the others, 

 which are moderately convex. Anal opening directed laterally. The food 

 grooves and their branches, respectively, are covered by a single plate. The 

 stem apparently was longer than in the two preceding species, and less taper- 

 ing. The nodal joints are a little wider than the intervening ones, which 

 increase very rapidly in number, there being six to the internode at an inch 

 from the calyx, which appears to be the maximum number. 



Horizon and Localitij. — Same as last. 



Types in the collection of "Wachsmuth and Springer. 



