LOWER HELDERBERG ROCKS. 191 



EcHiNOENCRiNiTEs ( Voii Mcycr) ; [ Sycocystites ( Von Buch) ; Gonocrinus ( Eich- 



wald) ; EcHiNosPH^RiTEs ( Pander)]. Body ovoid, often subangular, bearing 



pectinated rhombs. Basal plates four, with three succeeding ranges of five 



each. 



The principal species published are E. angulosus, E. anatiformis, E. armatus, E. bac- 



catus, E. fenestratus, E. giganteus, E. seckenbergi, E. striatus ; and several new species 



to be described in the forthcoming Reports of the Canadian Geological Survey. There is 



one undescribed species from the Hudson-river group. All of Lower and Upper Silurian age. 



Glyptocystites ( Billings). Body composed of four ranges of plates : basal plates 

 four; higher ranges five, with arms attached, and numerous pectinated rhombs. 



This last character is the distinguishing feature of the genus ; as these pore areas, or 

 pectinated rhombs, in other genera are three, or in three double or contiguous spaces. 



Species ined. Lower Silurian. 



Prunocystites ( Forbes). Body ovoid : basal plates four; second and third series 

 five plates each ; upper or apicial series unknown. Oral tentacles and pec- 

 tinated rhombs. 

 P.fletcheri : Upper Silurian. 



PsEUDOcRiNiTEs ( Pearce, 1842; Forbes, 1848). Body ovoid, composed of four ranges 



of plates, with an undetermined apicial range. Basal plates four, with three 



succeeding ranges of five each ; bearing pectinated rhombs, and arms with 



tentacles. 



P. bifaxcialus, P. magnifiais, P. oblongus, P. quadrifasciatus : Upper Silurian species. 



Apiocystites ( Forbes). Structure as in Pseudocrinites. 

 A. pentremitoides, A. elegam : Upper Silurian. 



Lepadocrinus ( Conrad ). Structiu-e essentially as Apiocystites and Pseudocrinites. 

 L. gebhardi : Upper Silurian. 



Sprerocystites ( Hall ). Botly spheroidal : base composed of four plates; upper 

 series unknown. Ovarian orifice superior. Arms numerous. Pectinated rhombs 

 as in preceding genera. 

 S. multifasciatus : Upper Silurian. 



Callocystites ( Hall ). Body ovoid : basal plates four; second series eight; third 

 series eight 1 Apicial plates undetermined. Arms and pectinated rhombs as in 

 three preceding genera. 

 C. jewelli : Upper Silurian. 



