96 



BULLETIN 64, UNITED STATES NATIONAL MUSEUM. 



Genus AGASSIZOCRIN US Troost. 



Agassizocrinites 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., 1, 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. 7a, 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 



