LOWER HELDERBERG ROCKS. 
151 
Echinoencrinites ( Yon Meyer) ; [ Sycocystites ( Yon Buch) ; Gonocrinus ( Eich- 
wald ) ; Echinosphjerites ( 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. giga?iteus, 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.Jletcheri : 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. 
t. bifasciatus, P. magnificus, P. oblongus , P. quadrifasciatus : Upper Silurian species. 
Apiocystites ( Forbes). Structure as in Pseudocrinites. 
A. pentremitoides, A. elegans : Upper Silurian. 
Lepadocrinus ( Conrad ). Structure essentially as Apiocystites and Pseudocrinites. 
L. gebhardi : Upper Silurian. 
SpHiERocYSTiTEs (Hall). Body 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. jewelti : Upper Silurian. 
