Contents. Vv 
Physics of Mountain Building; Some Fundamental Con- 
Peoviong. 2.8: MELLARD READE. oo de. 238 
Note on the Occurrence of Erratic Cambrian Fossils in the 
Neocene Gravels of the Island of Martha’s Vine- 
yard. ([lllustrated.] J.B. WoopworTH........ 243 
Isobases of Post-Glacial Elevation. BAron DE GEER... 247 
Bibliography of North American Vertebrate Paleontology 
for the year 1891. JoHN HYERMAN.,........... 249 
‘Observations on Llama Remains from Colorado and Kan- 
Bee N CURAGIN | cu eiestsieaeeve tik a0 ove wha ae 257 
Editorial Comment.—Progress of American Glacial Geology, 260. 
Review of Recent Geological Literature.—The Cause of an Ice-Age, Srr 
Robert Bayi, 261.—On the Lower Devonian Fish Fauna of 
Campbellton, New Brunswick, A. 8. Woopwarp, 263.—On the 
Characters of Some Paleozoic Fishes, E. ). Corr, 263.—Strati- 
graphy of the Bituminous Coal Field of Pennsylvania, Ohio and 
West Virginia, I. C. Wurrr, 264.—On a Group of Volcanic Rocks 
from the Tewan Mountains, New Mexico, and on the occurrence 
of Primary Quartz in certain basalts, Jos. P. Inprxes, 264—On a 
late volcanic eruption in northern California, and its peculiar lava, 
J.S. DILLER, 265.—The relations of the traps of the Newark sys- 
tem in the New Jersey region, N. H. Darton, 266.— Earthquakes 
in California in 1889, J. EP KEELER, 266 —A classed and annotated 
bibliography of fossil insects, 8S. H. ScuppEr, 266.—On the Bear 
River formation, CHARLES A. WHITE and the Stratigraphic portion 
of the Bear River formation, T. W. Stanton, 266.—Notes to ac- 
company a tabulation of the Igneous rocks, based on the system 
of Rosenbusch, F. D. ADAms, 267. —Report on the Sudbury Min- 
ing District, Canada, Rosert BELL, 269. 
List of Recent Publications, 270. 
Supplementary List of the writings of Alexander Winchell. 2738. 
‘Correspondence.—Arrow Points from the Loess at Muscatine, Iowa, F. M. 
WitrER, 276.—The Serpentines of the Coast ranges in California, 
M. E. WaApsworTH, 277.—Englacial drift of Long Island, JOHN 
Bryson, 287. 
Personal and Scientific News.—Prof. Wright’s lectures at Boston, 280.— 
Preparations for the sixth session of the International Congress 
of Geologists, 281.—Princeton Scientific Expedition of 1891. 
MAY NUMBER. 
An experiment designed to show the upward movement 
of sub-glacial debris. [[llustrated. ] OsstAn GUTHRIE. 283 
Preliminary descriptions of new brachiopoda from the 
Trenton and Hudson River groups of Minnesota. 
N. H. WINCHELL and CHARLES SCHUCHERT....... 284 
‘The drift of the North German lowland. Rotuuin D. SAt- 
SD UR) Yarn ee eiee a eck « -s, s'e SOR ORM R BR Stes oc stavtt ofemene: elec ctace’’s 294 
‘Gas wells near Letts, Iowa. F. M. Wirrer. ps 319 
‘Climatic changes indicated by the Glaciers of North rea 
ica. ISRAEL G Rmeamengue ws... sak inn 322 
Editorial Comment.—Sir Andrew C. Ramsay, Bark ‘336. 
