BATOCRINID^. 385 



medium size; extending beyond the tips of the arms. Structure of column 

 unknown. 



Horizon and Locality. — Upper Burlington limestone ; Burlington, Iowa. 



Batocrinus laura, var. sinuosus (Hall). 



I860. Actimcrims simiosm — Hall; Suppl. Geol. Rep. Iowa, p. 27. Photogr. plate (1872) 3.^, Kgs. 



8 and 9. 

 1873. Batocrinus siimosiis — Meek and Worthen; Geol. Rep. lUiaois, Vol. V., p. 368. 

 ISSl. Batocrinus sinuosus — W. aud Sp. ; Revision Palaeoci'., Part II., p. 168. 



This form is so closely allied to Batocrinus laura that we regard it 

 a variety of that species. It is said to differ in having a more pointed base, 

 a deeper groove between the two posterior rays, and that the interbrachials 

 of the anal side pass into the interambulacral plates, thereby approaching 

 Lohocrinus. The anal tube is moderately large and almost central. 



Horison and Loccdity. — Same as last. 



Ti/2:)e in the Illinois State collection at Springfield. 



ERETMOCRINUS Ltou and Cass. 



1859. Lyon and Cassedat ; Amer. Joum. Sci. and Arts, Vol. XXVIII. (ser. 2), p. 241. 



1866. Shdmaed (subgenus of Acli?iocrimts) ; Catalogue Palseoz. Foss. Part I., p. 359. 



1869. Meek and Woethen (subgenus of Batocrinus) ; Proceed. Acad. Nat. Sci. Pliila., p. 350. 



1873. Meek and Worthen (subgenus of Batocrinus) ; Geol. Rep. Illinois, Vol. V., p. 368. 



1878. W. and Sp. ; Proceed. Acad. Nat. Sci. Pbila., p. 235. 



1879. ZiTIEL (subgenus of Aetinocrinns) ; Handb. der Palfcontologie, Vol. I., p. 370. 



1881. W. and Sp. ; Revision Pala;ocr., Part II., p. 170 (Proc. Acad. Nat. Sci. Pliila., p. 344). 

 1885. W. and Sp. ; Revision Palajocr., Pari III., p. 113 (Proc. Acad. Nat. Sci. Pliila., p. 335). 

 1890. S. A. Millek; North Amer. Geology and Palffiout., p. 242. 

 Syn. Actinocrinus (in part), Hall 1860 and 1861. 



Calyx more or less depressed, broadly truncate at the base ; plates flat 

 or nodose, the surface sometimes granulated, but generally smooth. Basals 

 short, forming a broad rim, which projects conspicuously outward. Eadials 

 as large as or larger than both costals together. Costals two, short, wider 

 than long ; the first quadrangular ; the second pentangular or exceptionally 

 heptangular. The higher brachials in contact laterally, and forming a 

 continuous ring around the calyx. Arm facets directed horizontally; the 

 ambulacral openings arranged in groups ; respiratory pores well defined. 

 Arms from twelve to twenty-six. When there are more than twenty, the 

 addition is made in the posterior rays, the other rays having four each. In 

 species with less than twenty arms, the anterior ray has the least number. 

 Species with sixteen arms always have three in the posterior rnys. The 

 arms are paddle-shaped, narrow and rounded in the lower parts, broad and 



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