ACADEMY OF NATURAL SCIENCES. 167 



Ammonites or Ceratites from Oregon Bar, Middle Fork 

 of the American River. 



BY PROF. WM. P. BLAKE. 



The specimen which I exhibit to the Society this evening, is from the collec- 

 tion of J. J. Spear, of this city. It was kindly loaned to me by that gentle- 

 man for examination. Not wishing to risk the specimen, by sending it to a 

 paleontologist at the East, I had it photographed, and sent a copy to F. B. 

 Meek, Esq., of Washington. It is not possible to determine from the specimen, 

 whether these fossils are new or not, or even, whether they are Ammonites or 

 Ceratites. They appear to be not unlike the fossils described by Dr. Trask, 

 nnder the name of A. Chiceonsis, Proc. Acad. Nat. Sci. Cal. ; but it is not safe 

 to identify them, without the septae ean be clearly made out. 



There are several casts in an argillaceous, somewhat micaceous slate. This 

 locality is about 15 miles from Coloma. It is not certain, whether the speci- 

 men was taken from the slates in place, or broken from a loose mass. 



Mr. Moore presented the following paper : 



On Brushite, a new mineral occuring in Phosphatic 



Guano. 



BY GIDEON E. MOORE, PH. B. 



In the spring of the present year, I received through the kindness of Wm. 

 E. Brown, Esq., of Mare Island, in this State, a specimen of a mineral discover- 

 ed by him in a cargo of phosphatic guano, at Camden, N. J. The locality 

 from which it was derived, is not known, and though letters of enquiry have 

 been sent to the parties to whom the cargo was originally consigned, no reply 

 has been received up to this date. The texture and appearance of the guano 

 would, however, point to some one of the Carribbean Islands, and more par- 

 ticularly, to the Island of Sombrero, as its probable source. It is very proba- 

 ble that the mineral may be recognized among the crystallized products oc- 

 curring in other guano deposits. 



In the specimen in my possession, the mineral occurs filling seams in the 

 guano, varying from £ to J of an inch in width. The matrix itself is of the 

 variety known as rock guano. It possesses an oolitic structure and a brown- 

 ish white color, interspersed with small spots of pure white. 



The mineral is in the form of small but very perfect and brilliant crystals 

 with a cleavage in the direction of their greatest length, nearly equal to that 

 of selenite ; the laminae, being also slightly flexible, as in the case of the latter 

 species. Hardness, 2.25 (Moh's scale). Specific gravity, 2.208, (mean of two 

 determinations). Color, yellowish white. Transparent. Lustre, vitreous 

 splendent, inclining to pearly on the cleavage faces. 



When heated in a closed tube before the blowpipe, it whitens and gives off 



