88 Li, Like (GOIALIB C 
however, been seen with the appendages overlapping, both in the Nevada and 
in the Point Levis specimens. 
The lateral appendages of this species differ from those of C. wrightiz and 
C. oblongus in their much larger size, usually more rotund shape, and in the 
multiple marginal filaments. 
DAWSONIA NICHOLSON, 1873. 
Ann. and Mag. Nat. Hist., XI., p.139. Type, D. acuminata Nich. 
-Dawsonia monodon Gurley, sp. nov. Plate V., Fig. 4. 
Polypary somewhat rhomboidal in outline; Io to 14™™ long, 3 to 5™™ 
wide ad max., apex drawn out to a tapering mucro; dentate margin gently 
‘curving from apex to the blunter extremity, interrupted at junction of upper 
with middle third by a small acute tooth; non-dentate border obtusely 
-isosceles-triangular joined near its lower end by a groove that has run close 
beside and parallel to it; proximal extremity rounded. 
Horizon and locality.—Calciferous shales, Point Levis, Canada. 
Easily recognizable by the single tooth and its (for the genus) large size. 
Dawsonia tridens Gurley, sp. nov. Plate V., Fig. 5. 
Polypary elliptic in outline, 3 to 4™™ long and 1 to 1™™.5 wide, with the 
‘sharper extremity drawn out to a point; one margin bearing three acute 
teeth whose upper borders curve inwards, indenting the polypary and termi- 
~nating in a ‘‘pustule” ; opposite margin smooth, joined at a very acute angle, 
near its lower end, by a groove which has run downward close beside and 
-parallel to the margin. The blunt extremity rounded, grooved for a short 
distance. Substance corneous, thin. The denticles can be seen to extend 
tinto the polypary whenever a thin film of shale separates the adjacent margins 
“of successive teeth, and seem to indicate thece, but from the extreme tenuity 
«of the film it is not possible to determine this point definitely. 
Horizon and locality.—Calciferous shales, Point Levis, Canada. 
This species is marked off from all other by the tridentate margin. In 
outline and size it resembles most closely DY. acuminata Nich. 
THAMNOGRAPTUS HALL, 1859. s 
Pal. N. Y., Ill., p. 519. Type, 7. tygus Hall. 
Lhamnograptus barrandi Hall. 
.Rastrites barrandiz* Hall, Pal. N. Y., Ill,, 1859, pp. 520-521, with 
Fig.; Thamnograplus barrandit Lapworth, 1886, Tran. Roy. Soc. 
(Cain, ioe MIO, Wey SSCs Woy fOs UWS. 
This is certainly, as Lapworth says, a Zhamnograptus. A single specimen 
‘shows, scalariform-wise, the thecal mouth-openings. They occupy about 
The name Rastrites barrandii was preoccupied by Harkness (Quart. Jour. Geol. 
