634 THE CRINOIDEA CAJVIERATA OF A'ORTH AJIERICA. 



and their surfaces corrugated. Column rounded and stout ; the nodal joints 

 with undulated edges ; the axial canal moderately large and pentangular. 



Horizon and Locality. — Upper Burlington limestone j Burlington, Iowa, 

 and Quincy, Ills. 



Txjjie in the (Worthen) Illinois State collection, Springfield. 



Teleiocrinus tenuiradiatus Hall. 

 Plate LIX. Figs. 5 and 6. 



1861. Actinocrhms ienuiradiaiiis — Hall; Prelim. Descr. New Palieoz. Crin., p. 12. 



1873. Strotocrimis tetmiradiatus — Meek aud Wokthen ; Geol. Eep. llliuois, Vol. T.^ p. 349. 



1881. Teleiocrinus ieiiuiradiatm — W. and Sp. ; Ke'vasiou Palseocr., Part II., p. 149. 



A large species, remarkable for its broad rim, the great number of arms, 

 and the flatness of the plates. Calyx urn-shaped, its height about equal to 

 its greatest width. Dorsal cup to the base of the rim as long as wide, or 

 longer, the sides slightly convex. The rim rapidly spreading from the top 

 of the distichals, its outer margin at right angles to the axis of the calyx. 

 Arm openings directed somewhat upwards. Plates very little convex, almost 

 flat ; the suture lines distinctly grooved. The plates are covered with nu- 

 merous very fine and delicate striae passing from plate to plate ; they are 

 strongest at the sutures, where they form small pits at the intervening 

 spaces ; the plates are without nodes, and the ridges are generally less 

 conspicuous toward the middle. 



Basals large, forming a cup, which spreads more rapidly than the radials 

 and costals, and at midway is slightly constricted ; the lower margin sharply 

 angular, and the bottom concave. Radials a little longer than wide, and 

 more than twice as large as the costals, of which the first is hexangular, the 

 second a little smaller, and heptangular. Distichals almost as large as the 

 second costals. The palmars and succeeding brachials forming the rim grad- 

 ually decrease in size upward, all being wider than long, and almost flat. 

 There are from seven to eight bifurcations in each main division, or eighty 

 to ninety ai'ms to the species ; they are very much crowded, and roimded on 

 the back near the calyx ; upper parts unknown. Regular interradials eleven 

 to thirteen in five or six ranges, those of the upper row quite small. Anal 

 plate somewhat narrower than the radials, succeeded by fifteen or sixteen 

 plates. Ventral disk depressed above the rim, low-conical in the middle 

 portion.?, the sides gradually passing into a large central tube. Plates of 



