68 CANADIAN FOSSILS. 
G. SPECIES CONSISTING OF BRANCHES WITH SUB-CYLINDRICAL OR ROUNDED AXES; THE 
ULTIMATE PINNULA ELONGATE, SETIFORM, OR PLUMOSE, AND ALTERNATELY 
ARRANGED ON THE TWO SIDES OF THE AXIS OR LARGER RAMUS. 
Genus Prinoeraptus, Hall. 
Plate. Figure. 
up UMYOS US terrae veraretonelclataltstelals sielelo\(ela/slele/a/elelelera ntl ametatets 1-4 
GIMitZ anise peveror siete ayaa) oveia.'s wie: e.ete.e ece/everevelere 21 econo 5-8 
Genus THAMNOGRAPTUS, Hall. 
MME MOAN Ao Gao ooGddObosDFOORGODODODS 2b Gogg © 
SPECIES INTRODUCED FROM THE UTICA SLATE OF LAKE ST. JOHN, FOR COMPARISON 
AND ILLUSTRATION. 
GRAPTOLITHUS. 
Plate: Figure. 
G. (= Monoprion = Didymograptus) flaccidus..... 2 .... 17-19 
G. (= Diplograptus) quadrimucronatus...... Gonos opoa ae 
RETIOGRAPTUS. 
Plate. Figure. 
Retiopraptos CuCharis js,s,e0c0ce ee pra aciele seus sce'ee) LAT) tle nls 9 
§ I[.—DESCRIPTIONS OF THE SPECIES OF GRAPTOLITIDH FIGURED 
IN THIS MEMOIR. 
Genus GRAPTOLITHUS, Linneus. 
Generic Characters.—Polypidom or frond consisting of slender elongated 
stipes or stems, which are flattened and quadrangular, and may be simple 
or compound, and sometimes bifurcating. The cellules take their origin 
from a common body or canal, which is parallel to a slender axis. 
Some of the species have the cellules in single series, and others have 
them in two series, arranged on opposite sides of the stipe. 
Those species with the single series of cellules (Monoprion, = Mono- 
graptus) have the axis marginal; while those with the two series of 
cellules (Diprion, = Diplograptus) have each series entirely independant 
of the other and separated by a double solid axis, leaving no communi- 
