PALMOZOIC ROCKS IN CANADA AND SCOTLAND. 387 
are blunted and directed backwards. Length of the crest 1} line, 
from the large tooth to the point below ? line. 
This species is allied to A. lunatus (Pl. XIX. fig. 5), but differs 
therefrom in being wider and truncate, as well as in the form of 
the teeth. 
Summary. 
In the preceding pages I have described 55 different forms of 
jaws, of which there are 33 from the Cincinnati group, 13 from 
the Niagara and Clinton group, 7 from the Hamilton group, of the 
Canadian rocks, and 2 from the Lower Carboniferous in Scotland. 
The respective numbers included under the different genera are as 
follows :—Hunicites 14 forms, Ginonites 10, Arabellites 19, Stauro- 
cephalites 1, Lumbriconereites 4, Nereidavus 1, Glycerites 3, whilst 3 
forms are not referred to any genus. Of many of the forms there 
are numerous examples, whilst others are represented only as single 
specimens. Whilst there is thus shown a predominance of forms 
belonging to. the genera Hunicites, Gnonites, and Arabellites (on 
account of the number and variety of the different jaws in the 
individuals of these genera, which renders the work of classification 
to a certain extent doubtful), no definite conclusions can be drawn as 
to the relative abundance of the different genera. It is quite possi- 
ble that the number of species represented may be less than half the 
number of forms to which I have given names and descriptions, and 
they will therefore have to be accepted more for paleontological 
reference than as indicating so many separate species of these 
Annelids. It is possible that future discovery will bring to light 
some of these fossil Annelids with their jaw-plates in their respec- 
tive positions, which will enable many of the forms described to be 
placed under a single species ; in the mean time I have thought that it 
would be of interest to geologists to show, what had previously been 
inferred from the trails and markings, that Errant Annelids were 
very abundant in the Paleozoic rocks, and that, judging from their 
jaws, many of them were closely related to existing forms. 
EXPLANATION OF THE PLATHS. 
Puate XVIII. 
Fossil Annelid Jaws from the Cincinnati Group. 
Hig. 1. Hunicites major, H.: * 3. Toronto. 
3 
2, varians, Grinnell: * 6. Toronto. 
4. contortus, H.: * 8. Toronto. 
os varians, Grinnell: x 3%. Toronto. 
6. perdentatus, H.: X 15. Toronto. 
7. (Enonites curvidens, H.: * 15. Toronto. 
8. inequalis, H.: * 13. Toronto. 
9. serratus, H.: x 12. Toronto. 
10. rostratus, H.: * 15. Toronto. 
We cuncatus, H.: x 16. Toronto. 
12. Arabellites hamatus, H.: * 20. Toronto 
cornutus, HW.: * 12. Toronto. 
