PART I CHAZYAN AND RELATED BRACHIOPODS—-COOPER I9 
This view was expressed by A. E. Wilson (1932) as well as others. The lith- 
ology is completely unlike that of the Aylmer formation below, and the few 
fossils known are quite unlike those of the lower beds. The disappearance of 
the Rostricellula of the Aylmer sees the appearance of new types. Wilson records 
a number of species of Strophomena which is a genus not yet seen in rocks de- 
posited in the Marmor Stage. This genus, too, links the Pamelia to the over- 
lying Lowville. As a matter of fact it is doubtful if the formation is really sepa- 
rable from the Lowville here or elsewhere on a paleontological basis. 
Lowville formation.—In the Ottawa Valley the Lowville formation is 20 to 
30 feet thick and consists of the usual light-gray limestone with an occasional 
shaly bed. It abounds in the coral Tetradium cellulosum, and the trilobite 
Bathyurus extans is a common fossil. Brachiopods are numerous in the forma- 
tion and have been listed by A. E. Wilson (1946a, pp. 3-9) as follows: 
Dalmanella rogata (Sardeson) = Paucicrura rogata (Sardeson) 
Doleroides gibbosus (Billings) 
D. pervetus ottawanus Wilson = D. ottawanus Wilson 
Eridorthis rocklandensis Wilson 
Glyptorthis bellarugosa (Conrad). (Identification doubtful.) 
Lingula narrawayi Wilson = Lingulella narrawayi (Wilson) 
Opikina sinclairi Wilson 
O. subtriangularis Wilson 
O. tumida Wilson 
Rafinesquina alternata plana Wilson 
Rhynchotrema ainsliei (N. H. Winchell) = Rostricellula ainsliei (N. H. Winchell) 
R. increbescens (Hall). (Identification doubtful.) 
Schizocrania filosa (Hall) 
*Sowerbyella sericea (Sowerby) 
*Strophomena filitexta Hall 
S. venustula Wilson 
Zygospira recurvirostris (Hall) 
Correlation of Lowville formation—This formation is evidently the same as 
the Lowville of New York, but the list presented above contains numerous Tren- 
ton species and types. In the Appalachians Zygospira is very rare prior to the 
Witten (equivalent to Rockland), and typical Rhynchotrema increbescens is cer- 
tainly a post-Lowville (probably post-Rockland) species. 
Chaumont formation.—In the Ottawa Valley this formation had hitherto 
been called Leray formation (see below). It is a heavy-bedded, dark-gray lime- 
stone with some shale partings but little chert in its northern manifestation. The 
formation is about 30 feet thick. A E. Wilson (1946a, pp. 3-9) lists the follow- 
ing species: 
*Camerella hemiplicata (Hall) 
Dalmanella rogata (Sardeson) = Paucicrura rogata (Sardeson) 
Doleroides gibbosus (Billings) 
D. pervetus ottawanus Wilson = Doleroides ottawanus Wilson 
Eridorthis rocklandensis Wilson 
Hesperorthis tricenaria (Conrad) 
Lingula obtusa Hall = Genus ? 
L. rectilateralis Emmons = Genus ? 
