basoom.] LITERATURE. 87 
The reported rarity of volcanic action 1 in America in pre-Oambrian 
times is perhaps more apparent than real, and is due rather to the failure 
to recognize the results of such action than to the actual absence of vol- 
banic action. 
LITERATURE. 
A list of papers in which points of resemblance between ancient and 
modern acid volcanics have been emphasized, or in which devitrifica- 
tion has been described, and a list of articles on the nature and origin 
of spherulites, are appended. 
PArEKS ON ACID VOLCANICS AND DEVITRIFICATION. 
Allport, S. On the microscopic study of the pitchstoues unci felsites of Arran. 
Geol. Mag., Vol. IX, 1872, pp. 536-545. 
. On ancient devitrilied pitclistones and perlites from the Lower Silurian dis- 
trict of Shropshire. Quart. Jour. Geol. Soc, Loudon, Vol. XXXIII, 1877, p. 449. 
Bayley, W. S. Spherulitic volcanics at North Haven, Maine. Lull. Geol. Soc, 
Am., Vol. VI, 1894, pp. 474-476. 
Blake, J. F. Ou the felsites and conglomerates between Btdhesda and Llanllyfni, 
North Wales. Quart. Jour. Geol. Soc, London, Vol. XLIX, 1893, pp. 441-465. 
Bonney, T. G. On certain rock structures as illustrated by pitchstoues and fel- 
sites in Arrau. Geol. Mag., Vol. IV, 1877, pp. 499-511. 
. Note on the felsite of Brittadon, North Devonshire. Geol. Mag., Vol. V, 1878, 
pp. 207-209. 
. On some nodular felsites in the Bala group of North Wales. Quart. Jour. 
Geol. Soc, London, Vol. XXXVIII, 1882, p. 289. 
Boriiemann, T. G Die Quartzporphyre von Heiligeustein und seine Fluidalstruc- 
tur. Zeitschr. Deutsch. geol. Gesell., Berlin,Vol. XXXIX, 1887, p. 793. 
Chapman, F. On a method of producing perlitic and pumaceous structures in 
Canada balsam. Geol. Mag., Vol. VII, 1880, p. 79. 
Clements, J. Morgan. The volcanics of the Michigamme District of Michigan. 
Jour. Geol., Vol. Ill, No. 7, Oct.-Nov., 1895, pp. 801-822. 
Cole, Grenville A. J. On the artificial production of the perlitic structure. 
Geol. Mag., Vol. VIII, 1880, p. 115. 
. On hollow spherulites and their occurrence in ancient British lavas. Quart. 
Jour. Geol. Soc, London, Vol. XLI, 1885, p. 162. 
. On the alteration of coarsely spherulitic rocks. Quart. Jour. Geol. Soc, 
Loudon, Vol. XLII, 1886, p. 186. 
. On the devitrification of cracked and brecciated obsidian. Min. Mag., 
Vol. IX, No. 44, 1891, pp. 272-274. 
Cole, Grenville A. J., and Butler, G. W. On lithophysa; in the obsidian of the 
Roccho Kosse, Lipari. Geol. Mag., Vol. IX, 1892, p. 488. 
. On the lithophysa' in the obsidian of the Kocche Rosse, Lipari. Quart. 
Jour. Geol. Soc, London, Vol. XLVIII, 1892, p. 438. 
Davies, Thos. Preliminary note oh old rhyolites from Bouley Bay, Jersey. Min. 
Mag., Vol. Ill, 1880, pp. 118-119. 
Diller, J. S. Felsites and their associated rocks north of Boston. Proc Boston 
Soc. Nat. Hist., Vol. XX, 1880, pp. 355-368; Bull. Mus. Comp. Zool. Harvard Coll., 
Vol. VII, 1881, pp. 165-178. 
Futterer, Karl. Der Ganggranit von Gros-Sachsen und der Quartzporphyr von 
Thai im Thiiringer Wald. Inaug. Disser., 1890. 
Dana, J. 1)., Manual of Geology, 4th ed., 1895, p. 938. 
