64 THE GIANT TRILOBITE OF MOOSE RIVER. 
niart, who states “that the middle lobe of the abdomen is rarely 
more than 1-5 the width of the body.” But what is more re- 
markable, and still further distinguishes this animal remains 
from all other Asaphs,is the epidermal covering which concealed 
the terminal articulations of the tail. In our specimen there is 
no appearance of what has been called the membranous devel- 
opment beyond the lobes of the animal, another circumstance 
which seems to separate it from the genus Asaphus. The body 
is quite convex, and (page 38) both in breadth and length our 
fragment measures nearly three inches. 
I am indebted to the kindness of Dr. Charles J. Jackson, of 
Boston, Mass., for this interesting species: it occurs in magnetic 
iron ore, and was found by Dr. Jackson and Mr. F. Alger during 
their geological tour through Nova Scotia. Their highly im- 
portant memoir describing the mineralogy and geology of that 
part of North America, has been justly proposed as a model, both 
in its generalizations and its details, to future explorers of those 
districts ,of our country which yet remain unexamined and 
undescribed. According to this memoir, Nova Scotia is based 
upon granite, although that rock is almost every where covered 
by wore recent formations. A transition slate, with marine 
organic remains, and containing beds of limestone and rich 
deposits of iron ore, is very abundant. The iron ore is often 
beautifully impressed with organized bodies, of which our A. 
crypturus is a fine example. Sometimes one portion of a fossil 
is found moulded in the slate, and the other portion in the iron 
ore, thus indicating their contemporaneous formation. Sand- 
stone is next in extent after the slate, and it is said corresponds 
geologically with the new red sandstone or red marl of England. 
Dr. Jackson, in his letter which accompanied our fossil, remarks : 
“T send you a Trilobite from the mines of magnetic iron in 
Nova Scotia, which exist in the clay slate of Clements, on the 
Moose River, at Annapolis Basin; also a Terebratula found in 
the same locality. I beg you to show these specimens to the 
Geol. Soc. of Penn., and let me know the result of your 
decisions. The most extraordinary thing connected with these 
fossils is, that they were found in a magnetic iron ore, the pro- 
