ORINOIDS. 191 



Calyx large, somewhat urceolate, expanding above, mod- 

 erately convex ventrally ; above the costals extended into a 

 very marked horizontal rim, which is formed by theanchylosed 

 brachials up to the sixth order. Otherwise the forms of the 

 genus are like Actinocrinus. In ornamentation the species 

 vary considerably — some individuals showing well-defined 

 ridges radiating from the center of each dorsal plate, others 

 with the central nodosities large, and covering nearly the 

 entire area of each plate. 



Horizon and localities. — Lower Carboniferous, Upper 

 Burlington limestone : Ash Grove. 



The characters above enumerated are chiefly generic. 

 The species are distinguished from one another by their sculp- 

 turing principally. The thin, peripheral rim has led some wri- 

 ters to suppose that all the forms of this group are closely 

 related to and should be united with Strotocrinus; but this 

 view does not now appear to be the correct one. For, as sat- 

 isfactorily shown by Wachsmuth & Springer, the two sections 

 should properly be regarded as distinct generically, since in 

 the one the long anal tube unites it with Actinocrinus, and in 

 the other the anal opening is a mere perforation in the test. 

 Furthermore, morphological comparisons seem to indicate that 

 Strotocrinus was derived from Actinocrinus through Physeto- 

 crinus ; while the genus under consideration was an independ- 

 ent off shoot of the typical form of the family. 



Teliocrinusliratus (Hall). 



Plate xxiv, lig. 8. 

 Actinocrinus liratus Hall, 1851 : Geology Iowa, vol. I, Supp., p. 4, fig. 3. 

 Actinoc7-inus subumbrosus Hall, 1861 : Geology Iowa, vol. I, Supp. , p. 3. 

 Strotocrinus liratus Meek & Worthen, 1868 : Geol. Sur. Illinois, vol. II, 



p. 190. 

 Strotocrinus liratus Meek & Worthen, 1875: Geol. Sur. Illinois, vol. V, p. 



355, pi. vli, flg. 2. 

 Teliocrinus liratus Wachsmuth & Sprin^r, 1881 : Proc. Acad. Nat. Sci., 



Phila., p. 323. 



This species differs from T. umhrosus, chiefly in the orna- 

 mentation of the calyx, which consists of a series of sharp 

 parallel ridges passing from one plate to another, instead of 

 mere convexities. 



