INSERTAE SEDIS 443 



the primary plates of the rays consist of a radial and two or three primibrachs. It now 

 further appears that the right posterior radial is a compound plate, the superradial being 

 axillary, and supporting upon its left shoulder a series of plates which form the base of an 

 anal tube or sac, thus giving precisely the structure of the Inadunate genus Iocrinus. This 

 is definitely shown in two specimens, one of which is figured on Plate LXXVI, figure 24. 

 Now that this is understood, we find the same thing in Waagen and Jahn's figure 14 on their 

 plate 63, only the suture between the segments of the compound right posterior radial is not 

 drawn. Consulting my figure 24 on Plate LXXV, it will be seen that the basals are well 

 exposed, and the column obtusely pentagonal with the pentameres radial, indicating a mono- 

 cyclic base. These characters, along with the large radials and dichotomous arms, leave 

 nothing to separate the genus from Iocrinus, of which it is clearly a synonym. This conclu- 

 sion is reinforced by the stratigraphic position of the fossils, the Ordovician Stage d 4 of 

 Bohemia being correlated approximately with the American Trenton, in which Iocrinus 

 occurs as an exceedingly strong and persistent type. It ranges with only slight modification 

 of characters from the basal Trenton through the various Cincinnatian formations to the 

 close of the Ordovician, and into the Richmond beds of the Silurian. It occurs as a part of 

 a fauna which extends from the Cincinnati area through New York to Canada, and also in 

 northern Illinois, associated with a fauna which Dr. Ulrich informs me represents a different 

 migration. The latter occurrence shows greater differentiation of characters from the 

 others than they do among themselves. With the vigorous and long-lived form indicated by 

 this great time interval, it is not surprising to find its geographic range extending to the 

 eastward of the Atlantic basin. 



EDRIOCRINUS Hall 

 Plate LXXVI 



Edriocrinus Hall, Am. Jour. Sci. (Ser. 2), XXV, 1858, p. 278; Nat. Hist. New York, Pal. Ill, 1859, p. 119; 

 15th Rep. N. Y. St. Cab. N. H. 1862, p. 115 (sep. p. 87).— Meek and Worthen, Geol. Surv. Illinois, 

 III, 1868, p. 370. — Schlueter, Zeitsch. Geol. Ges. XXX, 1878, p. 59. — Wachsmuth and Springer, Rev. 

 Pal. I, 1879, p. 21 ; III, sec. 2, 1886, pp. 192, 262, 265 ; N. A. Crin. Cam. 1897, pp. 59, 145. — Chapman, 

 Classification of Crinoids, 1882, p. 4. — Zittel, Handb. Pal. I, 1879, p. 350. — Zittel-Eastman, Textb. 

 Pal. 1913, p. 206. — P. H. Carpenter, Ann. and Mag., May, 1883, p. 333. — Bather, Ann. and Mag. N. H. 

 (6) V, Apr. 1890, p. 332, May, p. 379; Rep. Brit. Assoc, for 1898, [1899.], p. 923; Treatise on Zool. 

 (Lankester), pt. Ill, 1900, p. 191. — Walther, Zeitsch. Geol., Ges. 1897, p. 47. — Talbot, Am. Jour. Sci. 

 (4) XX, 1905, p. 20. — Kirk, Eleutherozoic Pelmatozoa, Proc. U. S. Nat. Mus., vol. 41, 1911, pp. III- 

 114. — Springer, The Crinoid Genus Scyphocrinus, 1917, p. II. 



Crinoids without stem; either permanently attached directly by the base, 

 or free in the adult stage. Monocyclic ; BB 4, fused into a more or less hollow 

 mass (hereinafter simply called the base) with sutures usually obliterated by 

 secondary growth. RR in contact all around except at the anal side. Anal 

 plate in line with radials, usually projecting above their level. Radial facets 

 filling distal face of radials. Arms dichotomous. Pinnules probably wanting. 



Genotype. Edriocrinus pocilliformis Hall. 



Distribution. Lower Devonian, America. 



A brief discussion of this genus is advisable for the reasons, first, that Bather in the 



Lankester Zoology, 1900, referred it provisionally to the Flexibilia Impinnata ; and second, 



that I am now able to clear up certain structural points which have been in doubt, or 



obscured by erroneous interpretation. The latest formal diagnosis of the genus in 1905, 



29 



