ACTINOCRINIDiE. ' 591 



suture, and support the free arms. There are but two primary arms to each 

 ray, which branch three or four times at irregular intervals, the first bifurca- 

 tion taking place above the fifth to sixteenth double row of ossicles, the last 

 a short distance from the tips. Arms divergent, rather stout, and tapering 

 very little ; they are cylindrical, and above the second plate biserial, the two 

 proximal ones of the primary arms being cuneate. First interbrachials of 

 moderate size, rising to the height of the second costals ; the two plates of 

 the second row are to a large extent interambulacral, touching the distichals 

 but slightly at their lower ends. Anal plate a little longer than the radials, 

 and nearly as wide ; followed by three plates, of which the two outer ones 

 are as large as the single plate of the regular sides, the middle one smaller 

 and cuneate. The tegmen is, not shown in any of the specimens, being cov- 

 ered by the arms, but apparently it had no spines, or the points would be 

 visible at the ends of the arms. 



Horizon and Locality. — Waverly group; Richfield, Summit Co., Ohio. 



Tyj^es in the New York State Cabinet at Albany, N. Y. 



Amphoracrinus spinobrachiatus (Hall.). 

 Plate LXII. Figs. 1, ^, 3, 4.. 



I860. Aetinocrinus sjsinolracliiatns — Hall; Suppl. Geol. Ecp. Iowa, p. 6. 



1873. Amphoracrimis C^) spinobracMtitus — Meek and Wokthen; Geol. Eep. Blinois, Vol. V., p. 389, 



Plate 6, Figs. 5«, b, c. 

 1881. Amphoracrinus spinobracldatns ^— W. and Sp. ; Eevision Palseocr., Part II., p. 155. 

 Syn. Aotiiiomrms iitfiatus Hall; 1860, Suppl. Geol. Eep. Iowa, p. 20. 



Syn. Amphoracrimis ivfatus — Whitfield; Mem. Amer. Mus. Nat. Hist. N. York, Vol.1., p. 23, 

 Plate 2, Pigs. 10, 11 (not Aetinocrinus {Amphoracrinus) iiiflaius Hall, 1861, Boston Soc. Nat. 

 Hist., p. 2^i==Agaricocrimis infiatui). 



Calyx subpyramidal, distinctly lobed ; the dorsal cup shallow-saucer- 

 shaped ; almost flat, and in specimens with the arms preserved not visible 

 from a side view. Ventral disk nearly as high as its width at the arm bases, 

 inflated above the food grooves, and the lower part of the interambulacral 

 spaces depressed. The plates of the dorsal cup thin, their surface covered 

 with irregular, rather prominent rugosities, which are confluent, arranged in 

 rows, and form transverse ridges. The ridges upon the radials are crescent 

 shaped ; those of the first costals straight, while those of the second costals 

 and distichals are angular, their salient angles directed upwards, the ridges 

 upon the interbrachials less distinct, and longitudinally arranged. 



Basals forming a hexagonal, slightly projecting disk, which extends but 



