35 



variations of the rays witliin the calyx, which we think never take 

 place, except as a result of injury, and, therefore, of abnormal 

 development. If crinoids vary to "some extent," in this respect, 

 iu the same species, they may vary to a greater extent and all 

 the species may be thrown into one, under any particular genus. 

 This erroneous view seems to have been entertained by several of 

 the earlier authors when they described the crinoids, by the ring 

 of the plates, commencing at the basals and going upward, and 

 of course placing less and less value upon each succeeding ring, 

 and it has been perpetuated, especially among those who have 

 never given the subject much attention. Prof. James Hall was 

 correct in laying the stress he did upon the arm formula, as our 

 study and observation has led us to believe. 



The specimens illustrated are from the Burlington Group, at 

 Burlington, Iowa. The large one is in the collection of Wm. F. 

 E. Gurley, the smaller one in the collection of A. Albers. The 

 species is numerously represented in all collections from the 

 Burlington Group of Iowa and Illinois. 



BATOCRINUS INSOLENS, n. sp. 



Plate II, Fig. 1, azijgous side; Fig. 2, opposite view. 



Species medium or below medium size, biturbinate, calyx and 

 vault subequal in form and capacity, and together subelliptical in 

 outline. Calyx bowl-shaped, truncated below and rounded up 

 toward the arms; no radial ridges; plates convex and the larger 

 ones transversely nodose; diameter from one-third to one- half more 

 than the height. 



Basals form an hexagonal disc about one-half wider than the 

 diameter of the column, with an hemispherical columnar cavity 

 radiately furrowed. First radials large, about as long as wide, 

 three hexagonal and two heptagonal. Second radials quadrangular, 

 from two to two and a half times as wide as long. Third primary 

 radials larger than the second, four hexagonal and one heptagonal, 

 axillary, and, in the ray opposite the azygous area, supports on 

 each upper sloping side, three secondary radials, which gives to 

 this ray two arms. In the ray on the left of the azygous area, 

 and in the left lateral ray, the third primary radials support, on 

 each superior side, two secondary radials, the last ones of which 

 are axillary and bear upon each superior distal side two tertiary 



