96 BULLETIN 64, UNITED STATES NATIONAL MUSEUM. 



Genus AGASSIZOCRIN US Troost. 



Agassizoa-inites Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 1850, p. 62 

 (nomen nudum); MSS., 1850. — Owen and Shumard, Journ. Acad. Nat. Sci. 

 Phila. (n. ser.), 11,1851, p. 93; Geol. Rep. Iowa, Wisconsin, and Minnesota, 

 1852, p. 597. — Shumard, Marcy's Rept. Red Riv. Exped. Louisiana, 1853, 

 p. 173. — Hall, Rep. Geol. Surv. Iowa, I, Pt. 2, 1858, p. 684. — Shumard, 

 Trans. Acad. Sci. St. Louis, II, No. 2, 1866, p. 352.— Worthen, Geol. Rep. 

 Illinois, V, 1873, p. 556.— Meek, Amer. Journ. Sci., 3d ser., VII, 1874, 

 p. 484. — Zittel, Handb. d. Pal., I, 1879, p. 361. — Wachsmuth and Springer, 

 Rev. Palseocrinoidea, III, 1886, p. 262. — Miller, North Amer. Geol. and 

 Pal., 1889, p. 221.— Zittel, Text-Book Pal. (Eastman trans.), 1896, p. 162.— 

 Bather, A Treatise on Zool., Ill, the Echinoderma, 1900, p. 181. 



Astylocrinus Roemer, Leth. Geogn. (Ausg. 3), 1854, p. 229. — Dujardin and 

 Hupe, Hist. nat. Zooph. Ech., 1862, p. 159. 



The original description by Troost is as follows: 



GENERIC CHARACTERS. 



Pelvis — composed of five plates [infrabasals] terminating at the base in a solid point, 

 without cicatrice for a column. 

 Costals [basals] five, subhexagonal. 

 Scapulars [radials] five, pentagonal. 

 Arms [primaxils] five, pentagonal. 



Observations. — In Doctor Troost's formula the term arms is used 

 for arm plates or primaxils. The arms are ten in number, large, 

 uniserial and bear long pinnules. 



Genotype. — Agassizocrinus dactyliformis Troost. 



AGASSIZOCRINUS DACTYLIFORMIS (Troost) Shumard. 



Plate 12, fig. 1. 



Agassizocrinites dactyliformis Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 

 1850, p. 62 (nomen nudum); MSS., 1850. 



Agassizocrinus dactyliformis Shumard, Marcy's Rep. Red Riv. Louisiana, 1853, 

 p. 173, pi. i, fig. 7.— Hall, Rep. Geol. Surv. Iowa, I, Pt. 2, 1858, p. 685.— Shu- 

 mard, Trans. Acad. Sci. St. Louis, II, No. 2, 1866, p. 352 (catalogue name).— 

 Meek and Worthen, Geol. Surv. Illinois, V, 1873, pi. xxi, figs. 7«, b. — 

 Wachsmuth and Springer, Rev. Palseocrinoidea, III, 1886, p. 365 (cata- 

 logue name). — Miller, North Amer. Geol. and Pal., 1889, p. 221 (catalogue 

 name). — Keyes, Missouri Geol. Surv., IV., Pt. 1, 1894, p. 221. — Weller, 

 Bull. No. 153, U. S. Geol. Surv., 1898, p. 74 (catalogue name). 



The original description by Troost is as follows : 



This crinoid, as is seen in the figure, has an obtuse conical form and is composed of: 



Pelvis [base], — five plates ? irregular quadrilateral, two sides elongated and curvi- 

 linear, joining with the other plates, at the base in a solid point, two cycles forming 

 the superior part, joined with the other plates, form the circular superior border. 



Costals [basals]— five, subhexagonal, — they are placed in the reentering angles of 

 the circular border of the pelvis. 



Scapulars [radials], five pentagonal placed in the reentering angles of the series of 

 the costals [basals]. 



Interscapulars [anal plates] — five, small, irregular plates. 



Arms [primaxils], five, pentagonal supporting two hands [arms]. 



It is uncertain how the pelvis [base] is divided, — some traces of sutures are slightly 

 visible but they are so closely anchylosed that no reliance can be put on them, and 



