158 TRANSACTIONS OF THE [APR. 8, 
by these fossil resins when exhumed, particularly referring to 
that of copal. He had examined and collected many speci- 
mens bearing on the illustration of these external surfaces, 
and was convinced that they are all due to contraction of the 
resin during Jong burial and hardening. In copal, it is quite 
possible to trace the transition from evident contraction-cracks, 
by a gradually increasing complexity of intersections, to the 
stellate or so-called ‘‘ goose-skin ” marking, so characteristic of 
the fine grades of that resin. 
Further remarks were made by several members regarding the 
cutting of amber, etc. 
Mr. GeorGe F. Kunz spoke upon American ambers, and 
exhibited specimens of several, especially one of great beauty 
recently brought from Mexico. 
For the last fifteen or twenty years, travellers have occasionally 
brought specimens of a very remarkable amber from some loeality 
in Southern Mexico. The only information gained concerning 
it is that it is brought to the coast by the natives, who say that 
it occurs in the interior so plentifully and in such large pieces 
as to be used by them for making fires. The color of this amber 
is arich, deep golden-yellow, and when viewed in different posi- 
tions it exhibits a remarkable green fluorescence, similar to that 
of uranine or of certain petroleums. [A specimen was exhibited, 
belonging to Mr. M. T. Lynde, and measuring 4x3x2 inches. | 
It is perfectly transparent, and is even more beautiful than the 
famous so-called opalescent or green amber found at Catania, 
Sicily. 
This material would be extremely valuable for use in the arts. 
It is believed that an expedition has started for the locality 
where it is found in the interior. 
Mr. Kunz also gave the following notes on certain interesting 
minerals :— 
Through the kindness of a friend in India, the specimens of 
tabasheer which I exhibit (opalescent silicious masses found in 
the joints of the bamboo) were obtained at the Calcutta Fair, 
in November, 1888. This substance, though mentioned in all 
text-books, is very rarely seen here, and invites especial atten- 
tion, since it exhibits all the interesting properties shown in the 
