390 
GEOLOGY OF THE SECOND DISTRICT. 
100 . 
1. Bumastus trentonensis. 3. Illsnus trentonensis. 6. Ceraurus pleurexanthemus. 
2. Calymene senaria. 4. Sphaeroma bumastiformis (Eights). 7. Trinucleus tessellatus. 
5. Calymene. 
No. 1 has not been found in place ; the fine specimen from which the drawing was made, 
was found by a laborer in Hogansburgh, in a boulder of black bituminous limestone. The 
boulder is identical with the black limestone of Montreal, which contains the Trenton fossils. 
Upon the fragment containing the specimen, is discoverable a portion of a strophomena, 
known also to belong to this rock ; there can be no doubt, therefore, of the position which it 
occupies. But usually where a fossil has been obtained from a boulder, no account has 
been taken of it. No. 1 is allied both to Bumastus and Isotelus, or seems to be an interme¬ 
diate genus : it is probably a rare fossil. 
No. 2. The Calymene senaria is one of the most abundant fossils in this rock. In the 
Second district, it is found at Glen’s-Falls, Essex and Plattsburgh; and it is also found at 
Cumberland Head, or the opposite shore in Vermont, where the slaty limestone of the trenton 
rock is found. In some places, as at Essex, it seems to have congregated in immense num¬ 
bers : nearly a hundred heads, in an imperfect state, were observed upon one orthoceratite. 
This species has generally been mistaken for the Calymene hlumenhacliii, which belongs to 
rocks higher in the series. 
No. 3. For this small trilobite, I am indebted to my friend. Dr. Crawe, of Watertown. 
It seems to be rather rare, though it has been found in the valley of the Mohawk. The spe¬ 
cimen from which the drawing was taken, was found at Watertown. 
