176 Canadian Record of Science. 
ingly varied, the forms of life entombed in its strata 
belonging to almost all the classes of the Paleozoic fossils. 
No evidence of plant or fucoidal remains has been detected 
in the Utica of Canada. 
The mode of preservation of the fossil remains is similar 
to the manner in which most fossils are preserved in shales 
or finely divided clays and sands throughout paleozoic 
strata. The calcareous portions of the shells of brachio- 
poda, lamellibranchiata and cephalopoda, are preserved as 
such, but iron pyrites often replaces the lime, whilst the 
chitinous structure of crustaceans, graptolites, etc., is also 
replaced by iron pyrites in numerous instances. 
Amongst the most characteristic species which distin- 
guish this terrane from others, we find that trilobites play 
no unimportant part. In the lower half of the formation 
Asaphus Canadensis, Chapman—which may probably be 
identical with Hall’s A. latimarginatus described in 1847— 
may be said to be very abundant indeed. Thousands of 
fragments of different sized individua!s occur, which, when 
restored, would form individuals ranging from one inch to 
ten inches and more in length. The genus Triarthrus is 
also most characteristic of the Utica. In Canada the 
following forms occur: 7’. Becki, Green, 7. glaber, Billings, 
T. Canadensis, Smith, and 7. spinosus, Billings. Kmbryonic 
forms of this genus are very abundant in certain portions 
of the middle Utica about Ottawa, and a suite of specimens 
has been obtained, with few exceptions, similar to that 
obtained by Prof. Walcott, of the U.S. Geol. Survey, who 
has so admirably described the Utica of the United States 
and illustrated Triarthrus Becki in his “‘ Utica and related 
formation ”’ published in 1879. 
Triarthrus glaber is characteristic of the Utica outlier 
in the Lake St. John region, Quebec, whilst 7’. Canadensis, 
with its peculiar genal angle produced into a prominent 
spine on each side of the head, is most abundant in the Utica 
shales of the islands in the northern portion of Lake 
Huron, such as the islands north of Maple Cape, Xe. 
Triarthrus spinosus occurs intimately associated with 
