21; — The surface geology of Philadelphia and viciuity. 22. — Tu. D. Rand: 

 Od a belt of Steatite and Serpentine in Radnor Township, Del. Co. 37; — 

 Chromite near Radnor, Pa. 37; — On Randite. 3s ; — Some microscopic 

 enclosures in Mica. 40. — H. Carvill Lewis : On the Bryn Mawr Gravel. 

 41 ; — On tome enclosures in Mica. 42 ; — On dendrites. 42 ; — On a 

 jurassic sand. 43. — Th. 0. Rand: Potsdam sandstone near King of Prussia. 

 43. — Wm. W. Jefferis: A new locality for Amethyst. 44; — A new 

 Corundum locality. 44. — H. Carvill Lewis : The minerals of Surry Co. 

 N.C. 44. — J. M. Cardeza: Fossil (?) casts in sandstone. 44. — Th. 0. Rand: 

 On ä peculiar stratification in Gneiss. 44. — H Carvill Lewis: A new 

 locality for Lignite. 45; — On Serpentine in Bucks Co. 45; — The iron 

 ores and lignite of the Montgommery Co. Valley. 46; — On enclosures in 

 quartz. 56. — Wm. W. Jefferis: Menaccanite and Tale from Maryland. 

 56; — Sunstone in Labradorite. 56. — A. E. Foote: On a probable 

 pseudomorphism of Gummite and Uranotile after Uraninite. 56. — 

 H. Carvill Lewis: On a new fucoidal plant from the Trias. 57. — 

 Th. D. Rand : The northern belt of Serpentine in Radnor Township. 59. — 

 J. M. Cardeza : Garnet mistaken for Corundum. 59. — H. Carvill Lewis : 

 The Trenton gravel and its relation to the antiquity of man. 60; — On 

 Philadelphite , a new mineral. 74. — Reuben Haines: Analysis of Phila- 

 delphite. 74. — Fred. A. Genth, jr.: The so-called Emery ore from 

 Chelsea, Del. Co. 75. — Jos. Willcox: Some new mineral localities. 76. — 

 H. Carvill Lewis: On Philadelphite. 77; — On a Potsdam sandstone 

 ontcrop on the S* Valley Hill of ehester Valley. 93. 



19) Transactions of the American Institute of Mining En- 

 gine er s. Vol. VII. Easton. Pa. 1879. 8°. 



R. Neilson Clark: The Humboldt-Pocahoutas Vein, Rosita, Colorado. 

 21. — J. E. Chürch: The heat of the Comstock Mines. 45. — W. P. Blake: 

 Note on Zircons in Unaka Magnetite 76. — R. W. Raymond: The Jenks 

 Corundum Mine, Macon County. N. C. 83. — Ch. A. Ashburne : The Brad- 

 ford Oil District of Pennsylvania. 316. — J. F. Blandy: The Lake Superior 

 Copper Rocks in Pennsylvania. 331. — C. W. Kempton : Sketches of the 

 New mining district at Sullivan, Maine. 349. — F. Prime, jr.: A Catalogue 

 of official reports upon Geological Surveys of the United States and 

 Territories, and of British North-America. 455. 



20) Comptes rendus hebdomaires des seances de l'Acade- 

 mie des sciences. 4°. Paris. [Jb. 1881. I. —163—.] 



T. XCI. No. 18. 2. Novembre 1880. 

 Faye : Sur les orages volcaniques. 708. 



T. XCI. No 19. 8. Nov. 1880. 

 Edm. Hebert: Recherches sur la craie superieure du versant septen- 

 trional des Pyrenees. 744. 



T. XCI. No. 20. 15. Nov. 1880. 

 A. Delesse: Enrichissement des terres plombeuses, par un courant 

 d'air force. 791. — de Qüatrefages: Observations ä propos du livre de 



