RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 255 
6. Dark brown to black carbonaceous shale with Triarthrus 
spinosus, T. becki, T. glaber, Leptograptus annectans, 
Glossograptus quadrimucronatus, and other graptolites. 
Gloucester formation. (New Name). 50-75 
5. Interstratified limestone and dark shale. Characteristic 
fossils are Ogygites canadensis, Oxoplecia calhouni, Zygo- 
spira uphami, Plectambonites rugosus, etc. Collingwood 
formation. 25-30 
4. Thick-bedded dark gray limestone with very little shale. ; 
Characteristic fossils are Fusispira subfusiformis, F. 
nobilis, and many other gastropods, Cyclospira bisul- 
cata, Strophomena trilobata, and, in the lower part, Ra- 
finesquina deltoidea. Picton formation. 100 
3. Gray limestone, thin-bedded and with much interstrati- 
fied shale in the lower twenty-five feet, less shaly but not 
very thick-bedded above. “Prasopora beds” or true 
Trenton. In the shale at the base Clitambonites ameri- 
canus is the guide fossil, though many others are present. 
In the strata a short distance above these a profusion of 
echinoderms are found, among them being Pleurocystites 
squamosus, P. filitextus, Agelacrinites inconditus, and 
Comarocystites punctatus. Prasopora simulatrix is so 
very abundant throughout these strata that I have 
usually spoken of them as the Prasopora beds. 100 
2. Coarse-grained light gray thick-bedded limestone, 
thirty-three feet in thickness, resting upon sixty-six 
feet of blue to gray fine- to coarse-grained limestone con- 
taining great quantities of black chert in layers and 
flattened cakes. The upper beds contain an abundance 
of: Stromatocerium and Solenopora and in a nearby 
locality, Tetradiwm racemosum. The.lower beds have 
shaly partings in which great numbers of fine echinoderms 
have been found, particularly crinoids. Among the 
characteristic fossils are Edrioaster bigsbyi and Cleiocrinus 
regius. Hull formation. 100 
1. Thick-bedded dark gray limestone with partings of shaly 
limestone containing numerous fossils, among them 
Triplecia extans, Phragmolites compressus, Orthis dis- 
paralis, Strophomena filitexta, and Receptaculites occi- 
dentalis. This formation is not well exposed at Ottawa. 
Rockland formation. 35 
