32 A POPULAR EXPOSITION, ETC. 
Homalonotus.—This genus has the same num- 
ber of body-rigs as Oalymene, and the general 
shape, direction of the facial suture, &c., is also 
the same. The glabella, however, although con- 
tracted anteriorly, is without lobes, and the two 
longitudinally furrows, which impart a three- 
lobed character to the trilobites generally, are 
here but feebly developed. A common species 
of the Niagara Group, H. delphinocephalus is 
represented in Fig. 148. 
Fig. 148, 
Triarthrus.—This genus is also somewhat allied to Calymene, but 
the body-rings are fourteen, or from fourteen to sixteen, in number, 
and the head-shield and pleuree, in some species, 
terminate in points. The glabella is nearly straight 
at the sides, not much raised, and marked on each 
side by three short furrows. TZ. Bechii, (fig. 
149) of our Utica Schist formation, is the best 
known species. Impressions of the glabella of 
this form occur abundantly in the shale beds 
near Collingwood, and also in the neighbourhood 
of Whitby, C. W. In T. Beckii, each segment 
of the thorax bears in the centre a short spine. Fig. 149. 
In another species, made known by Mr. Billings 
under the name of T. spinosus, a long spine descends from the neck 
furrow of the glabella, and another from the eighth body-segment. 
A third species, 7. glaber (Billings), is destitute of spines. The 
two latter forms occur in the Utica Slate of Lake St. John, north of 
Quebec. 
Conocephalites.—In this genus, the gabella, 
though convex, is very short, and the body-rings 
are fourteen or fifteen in number. Its species 
are characteristic of the lowest fossiliferous 
deposits, and are mostly of very small size. 
The head-shield of C. Zenkeri, after Billings, 
is figured in wood-cut 150 (Can. Nat., vol. v., 
p- 205). It occurs in the Quebec Group of Fig. 150. 
Point Levi. 
Paradoxides.—Head-shield terminating posteriorly in horns; gla- 
bella well developed; body-rings over fifteen in number; pleure 
