1352.) 209 
AMBYSTOMA NEBULOSUM. 
Sp. Char. Head as broad as long, rounded in front ; palatine teeth in the form 
of a triangle, the apex directed forward; body brown with numerous yellow 
spots; tail longer than neck and body ; total length 5 inches 9 lines. 
Description. The head is large, depressed above, about as broad as it is long ; 
snout rounded; nostrils small, about three lines apart; eyes large and promi- 
nent; mouth very large ; tongue broad and flattened, free at its edges, attached at 
its anterior border; palatine teeth ~~~ shaped, the angle presenting forward, the 
extremities of the row being placed a short distance behind the internal nares ; 
neck contracted; posterior extremities stouter than the anterior; body sub- 
cylindrical, flattened inferiorly ; tail longer than the head and body, much more 
compressed, the posterior half especially, quite thin and rounded at its 
extremity. 
Color. Head brownish above, with numerous indistinct yellowish spots pos- 
teriorly; body blackish, presenting many yellowish spots upon the surface, 
the largest about a line in diameter; extremities blackish, mingled with yellow; 
tail of same dark hue, with numerous yellow spots and markings ; ; chin, throat 
and abdomen yellowish. 
Habitat. New Mexico. 
Dimensions. Length of head 8 lines; greatest breadth 8 lines ; length of neck 
and body 2 inches 2 lines; of tail 2 inches 9 lines; of anterior extremities 1 
inch 6 lines; of posterior the same; total length 5 inches 9 lines. 
Another specimen from the same locality is more uniformly blackish upon the 
upper surface, the yellowish spots being absent; the chin, throat and abdomen 
are also more distinctly marked with black and yellow. 
Remarks. The above species differs from the Proserpine of Baird and Girard 
in the shape of the head and in the coloring; and from Mavortia of Baird in 
the same particulars. ‘The Mavortia, according to Prof. Baird, has “about 
nine broad transverse bands of yellowish on the sides of the body, confluent to 
a certain extent with that on the belly.”? He describes similar markings upon 
the ,tail, forming nearly complete ellipses, about twelve in number. The 
Mavortia is eight inches in length. 
The Committee on the following paper by Dr. Genth, reported in 
favor of pnt ean in the Proceedings : 
On a probably new element with Iridosmine and Platinum, from California. 
By Dr. F. A. Genra. 
I received from Dr. Charles M. Wetherill a small quantity of white grains, 
which were collected in 1849-50 from California gold by the late Jos. R. Reynolds, 
Esq. An examination of these grains furnished me results which eG, perhaps, 
worth noticing. 
I. When treated with boiling hydrochloric acid, two grains began to dissolve 
with disengagement of hydrogen. As soonas I observed this reaction, I picked 
them out and washed them off with water. With a good magnifying glass I 
found that they were mechanically mixed with gold. Their color was between 
a tin-white and steel color; they were malleable, but harder than tin; they dis- 
solved in nitric acid, yielding a crystalline salt, the native gold which was mixed 
with them remaining undissolved. They precipitated copper from solutions but 
slowly. Hydro- -sulphuric acid precipitated the solution in nitric acid brown. A 
pure piece of the metal before the blowpipe on charcoal fused readily. It was 
soon covered with a black oxide and gave no incrustations. Borax inthe O. F. 
dissolved it and gave a colorless bead, which on cooling became opalescent the 
same reaction took place more readily inR. F. 
The quantity of this metal was too small for further experiments, but these re- 
