512 THE CEINOIDEA CAMERATA OF NORTH AMERICA. 



Horizon and Locality. — Lower Burlington limestone ; Burlington, Iowa, 

 and southern Missouri. 



Tyije, in the (Worthen) Illinois State collection. 



Agaricocrinus fiscellus (Hall). 

 Plate XXXVIII. Figs. 3a, I, c. 



1851. Actinocrinus fiscellus — Hall ; Bostoa Jouru. Nat. Hist., Vol. VII., p. 272. 

 18S1. Agaricocriaiis fiscellus W. and Sp. ; Revision Paleeocr., Part II,, p. 112. 



Of the same size as A. hrevis, and so closely resembling it that it is ques- 

 tionable whether it is not a mere variety of that species. It differs somewhat 

 in the proportions of the calyx, the dorsal cup being comparatively higher, 

 and the tegmen shorter. It is also more distinctly pentalobate, the inter- 

 radial depressions at the arm bases being deeper. In the ornamentation of 

 the plates the two species ai'e similar, if not identical. In the form under 

 consideration, the plates to the top of the radials are horizontal, and those 

 above curved abruptly upwards, with little increase in the width of the calyx. 

 The basals form a hexagon with a shallow depression in the centre for the 

 reception of the column, leaving the outer margins of the basal disk exposed. 

 Kadials wider than long, the upper part a little nodose, but without ornamen- 

 tation. There are two distichals in both divisions of the three anterior rays, 

 and also in one of the divisions of the two posterior ones ; while the divisions 

 next to the anal side have but one, which is axillary and supports at each 

 side a short palmar, making three arms to these rays against two in the 

 others. The arm facets are smaller than in A. hrevis; the arms not qnite 

 so heavy, but apparently a little longer. Tegmen very short, depressed 

 hemispherical ; the posterior oral large and sharply conical ; the other plates 

 slightly convex. The anal area is formed as in the preceding species, but 

 is somewhat more bulsfino'. 



Horizon and Locality. — Same as last. 



Tyjje in the University Museum at Ann Arbor, Mich. 



Agaricocrinus pyramidatus (Hah). 

 Plate XXXVIII. Figs. 4a, I, c, and 5a, I, c. 



1858. Actinocrinus pyramiclatus — Hall; Geol. Rep. Iowa, Vol. I., Part H., p. 565. 

 ISSl. Arjciricocrinus jiyramidatus — W. and Sp. ; Rerision Palieocr., p. 112 ; and 1893, Whitfield, Mem. 

 Araer. Mus. Nat. Hist., Vol. I., p. 23, Plate 2, Figs. 23 and 25. 

 Syn. Agaricocrinus corrugatus Hall; 1861; Prelim. Descr. New Palseoz. Foss., p. 4, and Boston 

 Joum. Nat. Hist., p. 283. 



