Metre, French, compared with an English yard, xxi, 382. Mexican Andes, ascent of Popocatepetl, xxviii, 220. Mexico, geological character, climate, uses of obsidian, &c. in, xvi, 160. ----, geological remarks relating to, _W. Maclure_, xx, 406. ----, discovery of mummies near Durango, xxxvi, 200. ----, silver mines of, xxiv, 226. ----, meteoric iron at Charcas, xxviii, 288. Mica, containing potash and lithia, xxxvii, 356. ----, analyses of lepidolite and a yellow, xxxvii, 361. ----, of Chester, Mass., crystallization of, viii, 250.^f ----, use of, in chemical analyses, xxiv, 373. ----, black, a substitute for glass in spectacles, xviii, 374. ----, models of crystals made of, xxxviii, 187. ----, in Canada, viii, 67. ----, in Connecticut, i, 353;--plumose, vi, 251. ----, in Massachusetts, i, 113; ii, 237; iv, 55 (green); vii, 255; viii, 41, 235;--prismatic, v, 399; vii, 30, 255; viii, 41; xiv, 219; --rose, i, 350; v, 265. ----, in New Hampshire, v, 40; xvii, 357. ----, in New Jersey, v, 246; vi, 250. ----, in New York, iv, 37; v, 29; ix, 40, 251; xxi, 326. ----, in Pennsylvania, ix, 45; xiv, 5, 13. ----, in Virginia, v, 257. ----, slate, association with granite, in Massachusetts, and relative age, vi, 4. ----, ----, varieties in the Connecticut valley, vi, 22. ----, ----, minerals of, vi, 24. ----, ----, in western Massachusetts, viii, 6, 240. ----, ----, relation to gneiss, viii, 6. ----, ----, conglomerated, in Windsor, Mass., viii, 7. ----, ----, contorted, viii, 253. ----, ----, minerals of, viii, 7. ----, ----, alternations with granular limestone, ii, 211; viii, 15, 240, 252. ----, ----, containing rounded pebbles of quartz, in Massachusetts, viii, 244. Mice, habits of, xlvi, 242. _Michaux, André_, notice of, _A. Gray_, xlii, 2. ----, notice of his botanical labors, ix, 266. ----, the younger, notice of, xlii, 10. Michigan, notice of the peninsula of, in relation to its topography, scenery, agriculture, population, resources and productions, _J. Pierce_, x, 304. ----, Indians of, _J. Pierce_, x, 313. ----, rocks of, xl, 136. ----, mining region of, _D. Houghton_, xli, 183. ----, Geological Reports on, of _D. Houghton_, noticed, xxxiv, 190; xl, 136. ----, geological and mineralogical observations on the northwest portion of Lake Huron; _J. I. Bigsby_, iii, 254.^f ----, geological and mineralogical observations of the region about Fort Winnebago, _D. Ruggles_, xxx, 1.^f ----, native copper and ores of, _D. Houghton_, xli, 185; xlv, 331, 332. ----, ---- ---- ibid, _D. Ruggles_, xlix, 64.^f ----, ---- ----, of Lake Superior, _H. R. Schoolcraft_, iii, 201.^f ----, ---- ---- and silver, of Kewenaw Point, _C. T. Jackson_, xlix, 81. ----, Lake, height of, xlv, 16; xlvi, 259, 260.