588 THE CRINOIDEA CAJVIERATA OF NORTH AMERICA. 



Amphoracrinus di-vergens (Hall). 

 Plate LXII. Figs. 5, 6a, b, 7a, h, 8a, h, e, 9, 10. 



I860. Adinocrinus divergeiis — Hall; Suppl. Geol. Rep. Iowa, p. 36. 

 1881. Amphoracrinus iivergens — W. and Sp. ; Revision Palseocr., Part IE,, p. 155. 



1893. Amplioracnms diverffens — WBllFiELD ; Mem. Amer. Mus. Nat. Hist. N. York, Vol. I., p. 21, Plate 



2, Pigs. 12, 13. 



Syn. Actinocrinus plambasilis Hall; Suppl. Geol. Rep. Iowa, p. 19, fignred in State Mus. Nat. 



Hist., BuU. I., Plate 4, Pigs. 10 and 11 ^ Amphoracrinus plambasilis M. and W. (Geol. Rep. 



Illinois, Vol v., p. 388). 



Sjn. Actinocrinus qmdrispinus "White, 1862, Proceed. Boston Soc. Nat. Hist., Vol. IX., p, 15 



^ Amphoracrintis quadrispinus'W. and M.; 1873, Geol. Rep. Illinois, Vol. V., p. 388. 

 Syn. Amphoracrinus divcrgens, var. multiramosus Meek and Wokthen, Geol. Rep. Illinois, Vol. V., 

 p. 388. 



Of rather large size. Crown in its natural condition, with all the arms 

 preserved, as wide as, or wider than, high ; the dorsal cup not visible from a 

 side view. Calyx subpyramidal, distinctly lobed above the first costals, the 

 interradial spaces deeply depressed between the free rays. Dorsal cup about 

 one third the height of the ventral disk, saucer-shaped, truncated at the base. 

 The rays from the second costals droop downward to the level of the bottom 

 of the calyx, and then, at about the top of the first palmars, they bend ab- 

 ruptly upward, and fold inward until the tips of the arms encircle the spi- 

 niferous summit of the di.sk, exposing the spines. The entire surface of the 

 calyx is covered with irregular granules or vermicular markings. 



Basals forming a slightly projecting, hexagonal disk, extending beyond 

 the sides of the column ; the suture lines distinct, but not actually grooved ; 

 axial canal small and sharply pentangular. Eadials all hexagonal, owing to 

 the straightness of the lower margins, and about once and a half as wide as 

 long. First costals almost horizontal ; wider than the radials and nearly as 

 long ; strongly inflected at the sides, and rounded exteriorly ; the upper face 

 semicircular in outline, and directed slightly downward. The succeeding 

 brachials constitute a part of the free extensions, and face more or less 

 downward. The second costal.?, which are a little smaller than the first, 

 are touched by the interbrachials only at their lower end.s, the lateral 

 upper parts of the plates resting against rigid ambulacral plates. Dis- 

 tichals various in number, but as a rule the two posterior rays have one 

 plate in each division, both axillaiy, and about as large as the second cos- 

 tals. They support at each side a large quadrangular palmar, which is fol- 

 lowed by a smaller cuneate one, and this by two rows of extremely short 



