J.'JS CATALOGUE OF THE BLASTOIDEA. 



imperfect septa (PI. X. fig. 8) is another instance of an approximation to Heterohlastus. 

 We have not been able to make out an hydrospire-plate in this genus, though it is 

 well developed in Granatocrinus (PL VIII. figs. 15, 20 ; PL X. figs. 11, 12, 14). 

 The differences between the two genera can be thus expressed : — 



Five spiracles, piercing the deltoids. An hydrospire- ) Granatocrinus. 

 plate. ' 



Eight (or ten X) small spiracles, grooving the edges of ) 



° , , , . , XT , , • , , f Heterohlastus. 



the deltoids. No hydrospire-plate. ) 



Genus GRANATOCRINUS (Troost, 1849 ; Hall, 1S62) 

 [emend. E. & C, 1882]. 



Mitra (pars), Cumberland (non Lamk.), Reliquiae Conservatse, 1826, p. 31. 

 Pentremites, G. B. Sowerby, Zool. Journ. 1825, vol. ii. no. 7, p. 316. 

 Pentatrematites (pars), G. B. Sowerby, Zool. Journ. 1828, vol. iv. no. 13, p. 89. 

 Orbitremites, J. E. Gray (MS.), Synop. Contents Brit. Mus. 42nd edit. 1840, p. 63. 

 Granatocrinites, Troost (MS.), American Journ. Sci. 1849, vol. viii. p. 420. 

 Granatocrinites, Troost (MS.), Proc. American Assoc. Adv. Sci. for 1850 [1851], p. 62. 

 Pentatrematites Elliptici (pars), Roemer, Archiv f. Naturgescb. 1851, Jabrg. xvii. Bel. i. p. 360. 

 Pentremites (pars), McCoy, Brit. Pal. Foss. 1851, fasc. 1, p. 123. 

 New Genus (pars), D. D. Owen, Wisconsin, Iowa, and Minnesota Geol. Report, 1852, 



p. 591 (note). 

 Pentremites (pars), Dujardin & Hupe, Hist. Nat. Zooph. Echinod. 1862, p. 89. 

 Granatocrinus (pars), Hall, Fifteenth Ann. Rep. New York State Cab. Nat. Hist. 1862, 



p. 146. 

 Elceacrinus (pars), Sbumard, Trans. St. Louis Acad. Sci. 1863, vol. ii. no. I, p. 112. 

 Granatocrinus (pars), Sbumard, Trans. St. Louis Acad. Sci. 1865, vol. ii. no. 2, p. 375. 

 Granatocrinus (pars), Meek & Worthen, Report Geol. Survey Illinois, 1866, vol. ii. p. 274. 

 Granatocrinus, Zittel, Handb. Pal. 1879, Bd. i. Lief. 3, p. 434. 

 Granatocrinus (pars), E. & C, Ann. & Mag. Nat. Hist. 1882, vol. ix. p. 236. 



Gen. Char. Calyx oval, orbicular, globose, or subglobose ; summit convex, 

 frequently contracted, and sometimes depressed ; base small, sometimes contracted, 

 with a central concavity of variable depth, seldom flat ; section pentagonal, round, or 

 roughly decagonal ; interradial areas more or less concave in most of the species, but 

 round or flattened in those having a decagonal section. Basal plates small, not visible 

 in a side view, but usually concealed in the central columnar cavity. Radial plates 

 of variable size, very short, of medium length, or extending more or less the whole 

 height of the calyx, but invariably turned in below to assist in forming the base ; 

 sinuses very long and sublinear, extending the whole length of the calyx, which usually 

 rests on the radial lips. Deltoid piates of variable size and form, usually unequally 

 rhombic, but sometimes triangular or arrowhcad-sluiped, large in some species, 



