22 Talbot — New York Helderbergian Crinoids. 



muth and Springer,* because there are no supplementary anal 

 plates in the calyx, as is the case in Agassizocrinus. Bather 

 lists the genus provisionally under the order Flexibilia^ an 

 order with no anal plate in the cup ; but, as Edriocrinus has 

 such a plate, the genus cannot be so referred. The calyx 

 structure is that of the Cyathocrinidse but there are differences 

 that prevent the reference of JEdriocrinus to this family. The 

 absence of a column is one of these differences and the manner 

 in which the rays divide is another. In Cyathocrinus, which 

 is the most representative genus of the family, the arms in 

 branching spread out irregularly, and the joints are generally 

 higher than wide ; while in JEdriocrinus the joints are very 

 short, and the arms branch as do those of Ichtkyocrinus, the 

 divisions remaining in contact and curling inward. The arms, 

 however, do not form a part of the calyx as in the last named 

 genus. 



Family description. — Calyx elongate. Base dicyclic, prob- 

 ably five fused plates in each order. Radials with facets for 

 the insertion of the brachials extending across the whole width. 

 Arms incurved, seemingly without pinnules, divisions remain- 

 ing in contact ; joints much wider than long. Column wanting, 

 the attachment being by the infrabasals in the young stages ; 

 mature forms unattached. 



Genus, JEdriocrinus Hall. 



Edriocrinus Hall. 



Edriocrinus Hall, Nat. Hist. N. Y., Pal., vol. iii, 1859, p. 119 ; 15th Kept. 

 N. Y. St. Cab. Nat. Hist., 1862, p. 115.— Meek and Worthen, Geol. Eept. 111., 

 vol. iii, 1868, p. 119.— Wachsnmth and Springer, Rev. Palgeocr., Pt. I, 1879, 

 p. 21, Pt. Ill, 1885, p. 10, and 1886, pp. 192, 265, 286 ; Proc. Phila. Acad. 

 Nat. Sci.. vol. xxxi, 1880, p. 244, vol. xxxvii, 1886, p. 232, and vol. xxxviii, 

 1887, pp. 116, 189, 210; N. Am. Cri. Cam., vol. i, 1897, pp. 59 and 145.— 

 Zittel, Handb. d. Pakeontol., I Band, 1880, p. 350.— P. H. Carpenter, Ann. 

 Mag. Nat. Hist., May, 1883, p. 333.— Bather, Kept. Brit. Assoc. Adv. Sci. 

 for 1898, p. 923 ; A Treatise on Zoology, 1900, Pt. III. The Echinoderma, p. 

 191. 



Amended generic description. — Caylx directly cemented, 

 either throughout life or only in the young stages, the attach- 

 ment being by the large infrabasals. The cicatrix very large 

 in some specimens and in others obliterated, by the accumula- 

 tion of calcareous matter on the outer surface of the calyx 

 plates. Infrabasals large, their height being from one-half to 

 two-thirds that of the cup as ordinarily found, completely fused 

 so as to destroy suture lines and to make the number of plates 

 uncertain. Basals five, height varying in proportion to that of. 



*Rev. Palaeocr., Pt. Ill, p. 192, 1885, or Proc. Phila. Acad. Nat. Sci., vol. 

 xxxviii, p. 116. 



fRept. Brit. Assoc. Adv. Sci. for 1898, p. 923 ; also The Echinoderma, p. 

 191, 1900. 



