290 CATALOGUE OF THE BLASTOIDEA. 



o-reater difference between it and the typical form than between our different examples 

 of 0. verm (PI. XV. figs. 1, 3) or of 0. pentangularis (PI. XV. figs. 6, 9). 



Locality and Horizon. Burlington, Iowa ; Lower Burlington Limestone, Subcar- 

 boniferous. [Hambach's locality is Sedalia, Missouri.] 



Okophoceinds verus, Cumberland, sp. 



(PI. XII. fig. 9 ; PI. XIII. fig. 16 ; PI. XV. figs. 1-4 ; PI. XVI. fig. 10 ; 



PI. XVII. fig. 13.) 



Mitra vera, Cumberland, Reliquiae Conservatae, 1826, p. 31, t. B. f. 1, 2. 



Pentatrematites inflata, G. B. Sby., Zool. Journ. 1829, vol. iv. p. 90, ibid. 1835, vol. v. t. 33, 



Suppl. f. 2. 

 Pentremites inflatus, Phillips, 111. Geol. York. pt. 2, 1836, p. 207, t. 3. f. 1-3. 

 Pentatrematites inflatus, Roemer, Archiv f. Naturgesch. 1851, Jahrg. xvii. Bd. i. p. 357 



(excl. syn. de Koninck). 

 Pentremites inflatus, Dujardin & Hupe, Hist. Nat. Zooph. Echinod. 1862, p. 92. 

 Pentremites inflatus, Rofe, Geol. Mag. 1865, vol. ii. p. 250, t. 8. f. 9. 

 Orophocrinus inflatus, E. & C, Ann. & Mag. Nat. Hist. 1882, vol. ix. p. 252. 



Sjj. Char. Calyx depressed pyriform, or balloon-shaped, expanding gradually 

 upwards from the base ; summit depressed convex ; section distinctly pentagonal, 

 with shallow reentering angles ; periphery either equatorial or nearer the base than 

 the summit. Basal plates long, large, convex, higher than wide. Radial plates 

 lar°-e, prominent, arched, occupying almost two thirds the entire height of the calyx, 

 longer than wide, narrowed below, with their surfaces in two unequal planes, the 

 upper one formed by the limbs being much the longer ; interradial sutures in wide 

 depressions : sinuses long and narrow, longitudinally arched, with simple margins. 

 Deltoid plates rhombic, small, as compared with the radials; the anal deltoid 

 obtusely rounded distally. Ambulacra long, narrow, and raised above the margins 

 of the sinuses ; ambulacral grooves broad at their proximal ends, exposing the lancet- 

 plates, but rapidly attenuating outwards ; lancet-plates large, shallow and boat- 

 slniped, occupying almost the whole width of the sinuses, deeply excavated for the 

 reception of the large side plates, which almost conceal them. Hydrospire-folds 

 seven to twelve ; tubes long and curved ; sacs pyriform. Spiracles narrow, extending 

 i ttemally along quite three fifths the length of the ambulacra, but shorter internally. 

 Anus oval, its distal margin projecting and lip-like, the proximal margin over- 

 hanging the aperture, after the manner of a hood. Ornament very fine and minute, 

 usually not preserved. 



Remarks. We are convinced that Mitra vera, Cumberland, and the subsequently 

 described Pentatrematites inflata, G. B. Sby., are identical. A perfectly clear, 

 although brief description, as well as a good figure, was given by Cumberland, and in 



