1852.] 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 neek 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 ..^^^"N^ shaped, the angle presenting for- 

 ward, the extremities of the row being placed a short distance behind the inter- 

 nal 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 some 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 of the belly." He describes similar markings upon 

 the tail, forming nearly complete ellipses, about twelve in number. The Ma- 

 vortia is eight inches in length. 



The Committee on the following paper by Dr. Genth, reported in 

 favor of publication in the Proceedings : 



On a probably new element with Iridosmine and Platinum, from California. 



By Dr. F. A. Genth. 



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. Rey- 

 nolds, Esq. An examination of these grains furnished me results which are, 

 perhaps, worth noticing. 



I. When treated with boiling hydrochloric acid, two grains began to dissolve 

 with disengagement of hydrogen. As soon as I observed this reaction I picked 

 them out and washed them oS" 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 metal before the blowpipe on charcoal fused readily. It was 

 soon covered with a black oxide and gave no incrustations. Borax in the 0. 

 F. dissolved it and gave a colorless bead, which on cooling became opalescent ; 

 the same reaction took place more readily in R. F. 



The quanlity of this metal was too small for further experiment, but these re- 



