F. Gabbro, east of Beverly Creek. Contains diallage and "basic" plagioclase, with pyrite and serpentine as alteration products.

G. Olivine-diabase, Camas Land. Contains augite, olivine, plagioclase, magnetite, and apatite.

H. Diabase, dike on ridge west of Turnpike Creek. Contains plagioclase, augite, olivine, magnetite, and apatite.

I. Basalt, middle fork of Teanaway River. Contains augite, plagioclase, magnetite, and apatite, with a glassy base.

ALASKA.

Rocks A to H, inclusive, were collected by G. F. Becker, who furnishes the petrographic data. A, B, C, D, F, and H are described by Becker in the 18th Ann., Part 3, p. 7. Analyses by Hillebrand, record No. 1585.

A. Augite-bronzite-andesite, Delarof Harbor, Unga Island. Greenish black. Contains plagioclase, near labradorite, with much smaller proportion of augite and bronzite, in a groundmass of plagioclase, with a little glass and much light-green indeterminate material. Contains 0.04 V2O3.

B. Augite-bronzite-andesite, St. Augustine Volcano, Cook Inlet. Purplish gray. Contains labradorite, augite, and bronzite, in a groundmass of plagioclase and magnetite.

C. Quartz-porphyry, bed of Bear Creek, 4 miles from its mouth, Turnagain Arm, Cook Inlet. Resembles D, with more feldspar and less quartz.

D. Quartz-porphyry, east of mouth of Indian River, Sitka, Baranof Island. Contains plagioclase, quartz, a little pyroxene, and some carbonaceous matter, with secondary quartz, calcite, and muscovite.

E. Diorite, head of Captains Bay, Unalaska Island. Contains plagioclase, biotite, hornblende, chlorite, magnetite, and sometimes tourmaline.

F. Diorite, Karluk Cliffs, Kadiak Island. Contains labradorite and hornblende, with subordinate quartz, biotite, and magnetite.

G. Diorite, Lane and Hayward mine, Silver Bow Basin. Contains plagioclase, biotite, hornblende, and scattering grains of quartz, with secondary chlorite, epidote, and muscovite.

H. Diorite, Treadwell mine, Douglas Island. Contains plagioclase, mostly albite, with secondary quartz, calcite, and pyrite, the latter apparently replacing ferromagnesian silicates. Contains 0.01 V2O,. I. Hornblende-andesite, Bogoslof Island. Described by Merrill in Proc. U. S. National Museum, vol. 8, p. 31. Contains hornblende, augite, plagioclase, tridymite, grains of iron ore, a little apatite, and probably sanidine. P. R. C. 315.

J. Like I, but darker colored. Contains more hornblende, no glass, and little or no tridymite. Same locality, also described by Merrill. Analyses I and J, by T. M. Chatard, record Nos. 209, 210. P. R. C. 316.

Rocks K to S. Collected by J. E. Spurr, who furnishes the petrographic notes. All but S are to appear in the 21st annual. Analyses

by Stokes, record Nos. 1809 and 1822.

K. Alaskite, Chilkoot Pass. Dike in granite. Contains quartz, orthoclase, and some twinned feldspars, accessory zircon, actinolite, magnetite, and siderite.

L. Alaskite-porphyry, Fortymile Creek, near Canyon Creek. Dike. Contains quartz, orthoclase, and some plagioclase, with accessory biotite and epidote.

M. Alaskite, Skwentna River, 12 miles above its mouth. Dike. Contains quartz, orthoclase, and microcline, with no dark minerals. N. Alaskite, Tordrillo Mountains. Dike. Consists of quartz, orthoclase, and microcline, with no dark minerals.

In K to N there are traces of P2O, but no CO,. Manganese is also present in

traces.

O. Andesite-oligoclase-scapolite-biotite rock, Skwentna River, 15 miles above its mouth. Dike. Essential constituents andesine-oligoclase, scapolite, and biotite, with accessory apatite and zircon.

P. Augite-belugite, Skwentna River, near Hayes River. Dike. Contains essential feldspar, intermediate between andesine and labradorite, augite, and some hornblende. Also a considerable amount of pyrite. Q. Tordrillite, Tordrillo Mountains. Dike. Contains phenocrysts of quartz, orthoclase, anorthoclase, and anorthoclase-albite. Groundmass consists of quartz and orthoclase. No dark minerals except very small quantities of secondary hornblende,

R. Augite-aleutite, near Kalinai Pass, Aleutian Peninsula. Lava. Chiefly labradorite, tending toward andesine, with a considerable amount of pale-green augite.

S. Tonalite-aplite, Yukon River, above Fort Hamlin. Dike. Consists essentially of quartz and soda-lime feldspars.