21 
from 8° to 15° 8. lat. This isa very inferior article, hardly 
exported at all. Second, the harder and better resin that is 
dug up in a partially fossilized state, in the same littoral re- 
gions in which the tree now flourishes. Third, the true fossil 
copal, forming most of that which is exported; this is found 
on the ancient beaches, 20 to 40 miles inland, and far from 
the modern habitat of this strictly shore-loving tree. There 
seems no question that the three varieties are all from the 
Trachylobium, but represent different stages of alteration. 
The true commercial copal, produced when the littoral tree 
grew at these points now so far from the sea, belongs of 
course to the “ era of elevated beaches,” corresponding to our 
Champlain epoch. The included insects, therefore, have a 
peculiar interest, as giving us remnants of the post-tertiary 
entomology of Eastern Africa. Prof. Martin stated that he 
had been giving a good deal of attention to this copal fauna, 
since reading Dr. Kirk’s account, and hoped to lay some 
material in regard to it before the Lyceum at no very distant 
day. 
With reference to the peculiar “ pitted” or “ goose-skin ” 
surface which is found upon most of the pieces of copal, he 
stated that there had been much discussion, and but little clear 
result. Consul Kirk finds it occurring on the,second and 
third of the varieties, that is to say, upon those that have lain 
long in the ground; but he had attributed it to the impression 
of grains of sand upon the buried resin, while the latter was 
yet soft. That such is not the cause, may be seen from the 
most superficial examination: the marking is perfectly regu- 
lar over the whole surface, and it consists not of depressions, 
butofelevations. This Dr. Kirk had more recently referred to, 
abandoning his previous view. Prof. Martin claimed that it 
is due to an alteration in the structure of the resinous mass 
in the course of fossilization, perhaps merely a long-continued 
contraction, at length covering the surface with regularly in- 
tersecting systems of cracks. He had sets of specimens illus- 
trating almost every stage of this process. A very similar, 
though slightly different, structure of the surface is seen in 
the early amber from the Cretaceous. 
