288 CATALOGUE OF THE BLASTOIDEA. 



Orophocrinus stelliformis, von Seebacb, Nachr. K. Gesellsch. Wissenscb. Gottingen, 1864, 



p. 110. 

 Codaster stelliformis, Sbumard, Trans. St. Louis Acad. Sci. 1865, vol. ii. no. 2, p. 359. 

 Codonites stelliformis, Meek and Wortben, Proc. Acad. Nat. Sci. Pbilad. 1869, p. 84 



(note). 

 Codonites stelliformis, Billings, American Journ. Sci. 1870, vol. 1. p. 232. f. 10, 11. 

 Codonites stelliformis, Meek and Worthen, Report Geol. Survey Illinois, 1873, vol. v. 



p. 464, t. 9. f. 5. 

 Orophocrinus stelliformis, Ludwig, Zeitscbr. f. wiss. Zool. 1878, Bd. xxxi. p. 389, t. 27. 



f. 30, 31. 

 Orophocrinus stelliformis, Zittel, Handb. Pal. 1879, Bd. 1. Lief. 3, p. 435, f. 309 a & b. 

 Orophocrinus stelliformis, E. & C, Ann. & Mag. Nat. Hist. 1882, vol. ix. p. 219. 



Sp. Char. Calyx pentagonal, balloon-shaped ; summit depressed, convex ; section 

 deeply pentagonal ; periphery almost equatorial ; base narrow, expanding gradually 

 to the basiradial sutures, and thence rapidly to the radial lips. Basal plates forming 

 a cup which is sometimes considerably wider than high, and more or less constricted 

 about its middle ; interbasal sutures very short. Eadial plates oblong, sides sub- 

 parallel; bodies concave in the middle line; lips much produced; interradial sutures 

 in depressions ; sinuses long and rather petaloid, tapering more or less at their distal 

 ends. Deltoid plates spearhead-shaped, constricted at about one third of their 

 length from the proximal end ; anal deltoid with its distal margin rounded. Ambu- 

 lacra long and subpetaloid, narrowing rather suddenly at about two thirds their 

 length from the peristome, raised above the margins of the sinuses ; lancet-plates 

 thick, broadly lanceolate, obtusely keel-shaped in section, and nearly filling the 

 sinuses, scarcely exposed, except in the median food-groove ; under lancet-plates 

 spatulate ; covering-plates often in a double series, and transversely elongated ; side 

 plates reaching fifty 1 on each side of an ambulacrum, triangular in section and much 

 bent down laterally, but almost meeting in the middle line. Spiracles more or less 

 curved, varying in length from one third to one half that of the ambulacra, largest at 

 their proximal ends. Five hydrospire-folds on each side of the ambulacrum. 

 Mouth very small, the summit plates minute and polygonal. Anus oval, bounded 

 distally by a projecting rim or margin. Top stem-joints often anchylosed together, 

 and filling the columnar cavity ; column unknown. Ornament generally obliterated, 

 and the surface smooth. 



Remarks. We have been guided in our description of O. stelliformis, irrespective of 

 the many specimens before us, by the excellent diagnosis given by Messrs. Meek and 

 Worthen 2 , but there are one or two points on which we differ from these eminent 

 Palaeontologists. We have never seen " supplemental basals," but we have 

 observed in a longitudinal section of a calyx the anchylosed upper stem-joints filling 



1 Fide Meek and Worthen. 2 Report Geol. Survey Illinois, 1S73, vol. v. p. 464. 



