12 
MUSEUM BULLETIN NO. 3. 
vician (Hudson River beds) and the Niagara limestone. 1 11 It 
has since been learned that he erred in including too much, 
since the lowest division of his Anticosti group belongs to the 
Ordovician and the upper two divisions to the Clinton and higher 
formations (Niagaran). The future employment of Billings' 
term requires its emendation and it appears to the writer that 
this should be done, since Billings gave the term its proper 
significance, erring only in including too much, and also in that 
the Anticosti section is far more complete and hence far more 
representative of this time than any other on the North American 
continent. This course has been followed in the present paper. 
In the final paper the matter will be more adequately treated. 
Silurian deposition was initiated by the formation of a 
yellowish-white limestone in which is recorded the almost com- 
plete disappearance of the species which had been so abundant 
in the Ellis Bay formation. The tabulate corals, however, 
form an exception, since they continue in almost undiminished 
numbers. The number of species decreases to thirty-nine, of 
which nineteen have come from below, consisting for the most 
part, of the Anticosti and generally well-known long ranging 
corals and brachiopods. In the lower half of the formation 
the number of species is few and none is abundantly represented, 
but in the upper portion there are more species and most are 
extremely abundant in individuals. Nineteen of the thirty- 
nine species are brachiopods. The thickness of the formation 
is 188 feet. The species present are: — 
1 Cyclocrinites halli 
2 Clathrodictyon vesiculosum 
3 Cyathophyllum wahlenbergi 
4 Diphyphyllum csespitosum 
5 Favosites forbesi 
6 F. gothlandicus 
7 Halysites catenulatus 
8 Lyellia affinis 
9 Paleofavosites aspera 
10 Zaphrentis stokesi 
11 Helopora concava 
12 H. formosa 
13 Pachydictya crassa 
14 Phsenopora superba 
15 Ptilodictya gladiola 
16 Atrypa marginalis 
17 Brachyprion leda 
18 B. n, sp. 
19 Camarotoechia neglecta 
20 Clorinda undata n. var. 
21 Cceiospira 
22 Crania 
23 Hindella 
24 H. 
25 Orthis 
planoconvexa 
n. sp. 
prinstana 
umbonata 
davidsoni n. 
var. 
26 O. ? flabellites 
27 Parastrophia lenticularis 
1 Billings, Rept. Progress 1853-1856, Geol. Surv. of Canada, 1857, p. 250, 
