256 



ECHINODERMA TA. 



[HYB. IOC. 



HYBOCYSTITES, Wetherby. 1880, Jour. Cin. 

 Soc. Nat. Hist., vol. 3, p. 150. [Ety. 

 hubos, humpbacked ; kustis, bladder.] 

 Calyx like Hybocrinus, and order of 

 arrangement of the 

 two series of plates 

 is the same, but dis- 

 tinguished by hav- 

 ing three arm-like 

 projections, and two 

 or more recumbent 

 arms with ambula- 

 cral opening central ; 

 from the peristome, 

 the five ambulacra 

 diverge ; three are 

 directed to the arm- 

 FiG. 342. Hybocy- i- k nrnWtirmq and 



stites problematicus. llKe projections, ana 

 are supposed to pass 

 over the top of them and extend down- 

 ward upon the exterior; valvular open- 

 ing between the upper azygous plate 

 and the mouth. Type H. problematicus. 

 problematicus, Wetherby, 1880, Jour. 

 Cin. Soc. Nat. Hist., vol. 3, p. 150, Tren- 

 ton Gr. 



HYDREIONOCRINUS, DeKoninck, 1858, Bull. 

 Acad. Royale Belgique, vol. 8, pt. 2, p. 

 13. [Ety. hydreion, water-bucket; kri- 

 non, lily.] Calyx short, rounded be- 

 low ; basals 5 ; subradials 5 ; radials 

 1x5; brachials 1x4 + 2x1; arms as in 

 Zeacrinus, and pinnules short ; distin- 

 guished from Zeacrinus by the ventral 

 sac, which extends beyond the arms 

 and covers them like a roof ; the upper 

 plates are convex or spinous ; respira- 

 tory pores in the sutures of the cylin- 

 drical part of the sac, which is covered, 

 by the arms. Type H. woodanus. 

 acanthophorus, Meek & Worthen, 1870, 

 (Zeacrinus acanthophorus,) Proc. Acad. 

 Nat. Sci. Phil., p. 28, and Geo. Sur. 111., 

 vol. 5, p. 563, Up. Coal Meas. 

 armiger, Meek & Worthen, 1870, (Zea- 

 crinus artniger,) Proc. Acad. Nat. Sci. 

 Phil., p. 27, and Geo. Sur. 111., vol. 5, 

 p. 547, Kaskaskia Gr. 

 depressus, Troost, as defined by Hall, 

 1858, (Zeacrinus depressus,) Geo. Sur. 

 Iowa, p. 546, Kaskaskia Gr. 

 discus, Meek & Worthen, 1860, (Zeacri- 

 nus discus,) Proc. Acad. Nat. Sci. Phil., 

 ), and Geo. Sur. 111., vol. 2, p. 312, 

 Pp. Coal Meas. 

 mucrospinus, McChesney, 1859, (Zeacri- 

 nus mucrospinuB,) Desc. New Pal. 

 FOBS., p. 10, and Trans. Chi. Acad. Sci., 



)7, and Geo. Sur. 111., vol. 5, p. 563, 

 al Meas. 



verrucosus, see Eupachycrinus verrucosus. 

 wetherbyi, Wachsmuth & Springer, 1886, 

 Revis. Palseocrinoidea, pt. 3, p. 245, 

 Kaskaskia Gr. 



HYPANTHOCRINITES, Phillips, 1839, Murch. 

 Sil. Syst. [Ety. upo, under ; anthos, 

 flower ; krinon, lily.] 

 cxlatus, see Eucalyptocrinus cselatus. 

 decorus, see Eucalyptocrinus decorus. 



&, 



fci 



Hystricrinus, Hinde, 1885, Ann. and Mag. 

 Nat. Hist., p. 158, syn. for Arthracantha. 

 carpenteri, see Arthracantha carpenteri. 

 ICHTHYOCRINUS, Conrad, 1842, Jour. Acad. 

 Nat. Sci. Phil., vol. 8, p. 279. [Ety. 

 ichthys, fish ; krinon, lily.] General 

 form, including incumbent arms, ovoid 

 or pear-shaped ; calyx cup-shaped ; ba- 

 sals 3 ; subradials 1x5 jjprimary radials 

 3 or 4 x 5, short and increasing, in 

 width, upward ; secondary and tertiary 

 radials similar in form to the primaries ; 

 arms 40 to 60 or more. Type 

 I. laevis. 



burlingtonensis, Hall, 1858, 

 Geo. Sur. Iowa, p. 557, Bur- 

 lington Gr. 



clintonensis, Hall, 1852, Pal. N. 

 Y., vol. 2, p. 181, Clinton Gr. 

 corbis, Winchell & Marcy, 1865, 

 Mem. Bost. Soc. Nat, Hist,, 

 vol. 1, p. 89, and Jour. Cin. 

 Soc. Nat. Hist., vol. 4, p. 175, Ni- 

 agara Gr. 

 he vis, Con- 

 rad, 1842, 

 Jour. Acad. 

 Nat. Sci., 

 vol. 8, p. 

 279, and 

 Pal. N. Y., 

 vol. 2, p. 

 195, Ni- 

 agara Gr. 

 n o b i 1 i s . 

 Wach- 

 smuth & 

 Springer, 

 1878, Proc. 

 Acad. Nat, 

 Sci., p. 254, 

 Upper Bur- 

 lington and 

 K e o k u k 

 Q r FIG. 344 Ichtbyocrinns Isevis. 



subangularis, Hall, 1863, Trans. Alb. Inst., 

 vol. 4, p. 207, and llth Rep. Geo. Ind., 

 p. 268, Niagara Gr. 



tiariformis, Troost, as defined by Hall, 

 1858, (Cyathocrinus tiariformis,) Geo. 

 Sur. Iowa, p. 558, Subcarboniferous. 

 Icosidactylocrinites. Not defined. 

 IOCRINUS, Hall, 1866, Advance sheets, 24th 

 Rep. N. Y. St. Mus. Nat. Hist., p. 212. 

 [Ety. io, in triumph ; krinon, lily.] 

 Calyx pentag- 

 onal, pyra- 

 midal sides 

 deeply con- 

 cave ; basals 

 5, indented 

 downthemid- 

 dle ; radials 

 3 to 6 x 5 ; 

 arms long, 

 frequently bi- 

 furcating, but bearing no pinnules; 

 ventral sac very long, extending be- 

 yond the arms, subcylindrical longi- 



FiG.345. locrinus. Diagram; 

 b, basals ; r, radials ; a, azy- 

 gous plate; t, plates of 

 tube. 



