366 G. J. HINDE ON CAMBRO-SILURIAN 
PotyenatHus? ERrIENSIS, Hinde. (Pl. XVII. fig. 6.) 
Tooth or jaw formed of an oblong, compressed plate, with ten 
stout, blunt teeth on its upper border. This plate is attached nearly 
at right angles to a chitinous appendage, nearly of a triangular form, 
whilst the toothed portion of the jaw is of the usual brownish semi- 
translucent character common to the majority of the Conodonts ; 
the appendage has a black chitinous appearance. Length 12 line. 
Loc. From an erratic nodule of black Genesee Shale on north 
shore of Lake Erie, Ontario. 
PotyenatHus? curvatus, Hinde. (Pl. XVII. fig. 7.) 
Tooth or jaw formed of a wide, oblong, slightly curved plate with 
about fourteen blunt teeth or crenulations on the upper border; this 
plate is attached at right angles to a compressed, sickle-shaped, grooved 
appendage of a similar structure to that of the preceding species, 
from which, however, it differs in shape. Length 17 line. 
I have only met with a single specimen. 
Loc. Bear Creek, Ontario: Genesce Shale. 
PoryeNnaTHus PENNATUS, Hinde. (Pl. XVII. fig. 8.) 
An elongated oval plate with a longitudinal depressed furrow, in 
the centre of which rises a slender keel, which is produced beyond 
the main portion of the plate and has a few blunt tubercles on its 
crest. ‘Transverse ridges run from the outer edge of the plate to 
the central furrow. Abundant. 
Loc. North Evans, New York: from the ‘‘ Conodont-bed” of the 
Hamilton group. 
PoLYGNATHUS TUBERCULATUS, Hinde. (PI. XVII. figs. 9 & 10.) 
Plate somewhat circular in outline, with a prominent central 
keel produced and tuberculated ; in the lower portion of the plate 
is a partially detached lobe on either side of the central line; the 
plate is provided with rows of tubercles which converge towards the 
centre. The reverse side of a form which appears to belong to this 
species (fig. 10) has a central ridge with a small diamond-shaped 
pit just below the centre of the plate; the surface of this reverse 
side is smooth, with traces of concentric lines. Length of plate and 
keel Z line, and 3 line in width. 
Loc. North Evans, New York: from the ** Conodont-bed” of the 
Hamilton group. 
Potyenaruus cristatus, Hinde. (Pl. XVII. fig. 11.) 
Plate oval in outline, depressed, convex; the central keel very 
prominent and with stout teeth or crenulations on its crest; on the 
plate are two rows, on either side of the central keel, of prominent 
tubercles. Length 7 line, width 3 line. 
Loc. North Evans, New York: from the ‘‘ Conodont-bed.” 
Potyenatuus TRuNcATUS, Hinde. (Pl. XVII. figs. 12 & 13.) 
Plate cordate in outline, with a median keel which is not continued 
