1880,] NATURAL SCIENCES OF PHILADELPHIA. 331 



roots and spicuke ; covered with long birotulate spicula^ radially 

 arranged ; foramen elongated into a tube flaring at its extremity 

 and dividing into 2 — 5 tapering, slender, curling or twisted tendrils, 

 believed to be as much as half an inch in length. The sareode 

 decomposes early in the season and most of the skeleton spiculte 

 are then washed awa^^ ; but these tendrils hold the mass of 

 spheruUie attached to the roots etc. above mentioned, awaiting the 

 spring germination. For this curious species he suggested the 

 name S. tentasperma or tendril seeded. 



Dr. M. S. De Bey of Aix-la-Chapelle and Prof. Torquato 

 Taramelli of Pavia were elected correspondents. 



August 3. 

 The President, Dr. Ruschenberger, in the chair 

 Sixteen persons present. 

 The death of James Ridings, a member, was announced. 



Notes on Jarof^ite. — Prof. George A. Konig communicated his 

 <liscovery of Jarosife at the " Iron Arrow Mine,'' in Chaffee Co., 

 Colorado. 



The mineral occurs there in seams and cavities of silicious 

 thurgite and hematite, which iron ores crop out on the steep side 

 of a Porjihyry hill about (lOO feet above the Arkansas Rive]-, flow- 

 ing at a distance of two miles to the south. 



The mineral appears in small, but Aery brilliant cr3''stals, isolated 

 and in groups ; also as aggregations of crystals which produce 

 crusts. It is remarkably crystalline, since no compact, or crypto- 

 crystalline masses were observed. 



The crystals are rhombohedrons (resembling cubes), modified 

 by the basal plane. The speaker had not observed as yet a crys- 

 tal of sufficient size to be accurately measured. Hardness slightly 

 above selenite ; color, from light amber-yellow to deep brown. 

 Perfectly transparent. Lustre of crystal faces adamantine, resin- 

 ous on the fracture. Sp. gr. = 3.144. 



The material used for analysis consisted of the aggregations 

 before mentioned, which showed an admixture of chalcedony and 

 of brilliant, black grains of thurgite ; these could not be separated 

 mechanically, being too small. 



The mean of two analyses gave : 



100.80 



