On North American Spiders. 99 
ped with this rock, which seems to resist the action of the weather, 
better than those with which it is associated. 
Magnetic iron ore is found in the Highlands, in very numerous 
beds and veins, in gneiss, and sometimes in other rocks. Copper 
and iron pyrites generally accompany it, in small quantity, as well as 
augite, hornblende and its varieties, and some other minerals. Four 
of these ore beds, only, are wrought to much extent. 
Magnetic iron sand covers the shore, three fourths of a mile north 
of Cold spring landing ; but it may be seen almost any where in the 
Highlands, after a rain, by examining where the water has washed. 
In the red limestones of the Highlands, scapolite, hornblende, and 
phosphate of lime, are usually associated, and in the white ones we 
find brucite, and spinelle, or graphite, mica, and hornblende; and 
where serpentine is in connexion with the limestone, we usually find 
diallage, amianthus, diopside, and the coccolites, white, red and green. 
ith the augite rocks, we find fine glassy feldspar and adularia, 
with mica, sometimes in six sided prisms; scapolite, crystallized and 
massive, sphene, and copper and arsenical pyrites in small quantities. 
Blende and carbonate of zinc are occasionally found, in loose masses, 
but I have never seen them in place. ; 
Sulphuret of molybdenum is found in small quantity, and wherever 
Thave seen it in place, in the Highlands, its matrix is a milky quartz, 
forming beds or partings of small extent between the strata of gneiss. 
Sulphurets of lead and silver, are said to have been found; but 
Thave never seen them in place.) 
Thave said nothing concerning the order of superposition, in the 
‘ocks in the Highlands, because I am not perfectly satisfied as to 
their relative position. 
Sr 
Arr, AUT —On North American Spiders; by N. M. Henrz, Prin- 
“pal of the Female Seminary at Covington, Kentucky, and late Pro- 
&ssor of Modern Languages in the University of North Carolina. 
Letter to the Editor. ‘: 
Amherst College, August 22, 1831. 
‘ PROFESSOR SILLIMAN, 
Stm—Some time since I addressed a request to Nicholas M. Hentz, 
its then Professor of Modern Languages in the University of North 
atolina, and now Principal of the Female Seminary in Covington, 
Kentucky ; that he would furnish me with a list of the Ananzipgs 
