There seems now, however, to be a growing consensus of opinion that these breccias are Permian. If this should prove so, it will only be needful that the conclusion be modified by restriction; when we should have to assign the great series of Devonian igneous rocks which have the granites at one end and the andesites at the other, to a period between the Lower Carboniferous and the Permian (to some extent inclusive).

It seems a question whether the "gabbros" in the Tavistock and Mary Tavy district, and some at least of our intrusive dolerites, may not be connected with a still earlier period of the same range of igneous activities, but I cannot deal with that now.

The list which follows is arranged alphabetically under the names of places-the only method that seemed to answer the purpose in view. When no definite localities are given it may be assumed that the examples occur either in beds of streams or alluvial deposits. The descriptions are purposely (and necessarily, seeing that over 400 varieties are dealt with) simple and macroscopic. Granite is used in its ordinary acceptation; felsite for all rocks with a felsitic matrix; pegmatite for quartz-felspar rocks; greisen for quartz-mica-; luxulyanite for felspar-schorl-; micas generally are described by their colour, and no attempt is made to discriminate between the felspars. The main object has been to give the general composition and physical characters in a plain and succinct form; and to this other details have been subordinated. Finally it must be borne in mind that the list is one of rocks, not localities, and does not profess to be exhaustive.

close-textured, but

Avon Valley (Black Tor).-Bluish-grey developing modified porphyritic characters, both felspathic and quartzose, with a sprinkling of schorl, evidently replacing mica.

Avon Valley (Black Tor).-Pinkish-brown: differs from the last almost wholly in colour, but is somewhat less disposed to the porphyritic phase.

Avon Valley (near Whiteaburrow).-Reddish-brown fine evengrained slightly schorlaceous pegmatite.

Avon Valley (ditto).-Pink, weathering to cream: fine-grained pegmatite, with porphyritic quartz blebs, occasional porphyritic felspars, and frequent stellate aggregations of schorl.

Avon Valley (ditto).-Reddish-brown fine even-grained granite with black mica, and occasional porphyritic felspars of a lighter hue; some schorl, occasionally segregated and, less frequently, pseudomorphic.

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Avon Valley (near Ryders Rings).-Dark-red to reddish-grey this rock has little resemblance to ordinary granite, the base consisting of a granular aggregate of quartz and ferruginous matter, with occasional flecks of white mica; but it contains porphyritic crystals of felspar and quartz. Some of the ferruginous material has decayed and left the texture of the rock open; probably it replaces an iron mica.

Avon Valley.-Brownish-red: even-grained schorlaceous pegmatite, with veins.

Avon Valley.-Grey, creamy: finely-granular pegmatitic base, with occasional blebs of quartz and porphyritic felspars, and here and there a nest of schorl, or a little needle that may replace mica. Avon Valley.-Red-brown: massive jaspideous quartz-porphyry. Avon Valley.-Red-grey: coarse-textured but compact granite, with red felspars, many well-twinned, black and white micas, and schorl.

Avon Valley.-Dark red-brown: uneven-textured, compact granite, with black mica and rich Indian-red felspars.

Auswell Rock.-Grey and brown: a somewhat open-textured (having small irregular cavities) sub-crystalline quartzose rock. Bel Tor.-Pale red crystalline schorlaceous granite; small content of mica, but schorl generally present and developed in prismatic aggregates.

Bickleigh Vale (in situ).—Warm-buff: compact felsite, saccharoid grain with an occasional small pyramid of quartz.

Blackett (near Wrangaton).-Buff: loose-textured medium-grained granite with abundant black mica.

Blackett.-Warm-grey: (a) sub-granular felsite approaching an earthy texture, with small porphyritic granules of quartz and needles of schorl; (b) coarser and less compact variety; (c) chalky-weathering ditto.

Blackett. - Buff: fine-grained granitic matrix with partly kaolinised felspar, porphyritic quartz and a little black mica and schorl; associated with pegmatite of similar texture, and large porphyritic felspars.

Blackett, (near)-Creamy-pink sub-crystalline felspathic rock with casual schorl and porphyritic characters; the felspathic base is graphically mottled red and cream.

Bovey Tracey-Grey; a fine grained felsitic pegmatite, in parts rather porcellanous: the felspar largely kaolinised. Brattor (near Bridestowe)-Pale red a

: coarse schorlaceous pegmatite; felspar largely predominating; crystalline forms both in quartz and felspar; some of the latter patched greenish-grey. Brattor-Red: moderately coarse-textured pegmatite, with porphyritic blebs of quartz and occasional nests of black mica.

Brazen Tor (Mary Tavy)-Pink: fine granular pegmatite. Cann (on the Plym)-Cream colour: very finely-granular elvan with occasional distinct quartz and white mica; calcite and pyrites developed on joint faces. This is in situ in Cann Quarry, and like others of its class is really an aplite. Cattedown detritus, found in 1887-1888 on the northern slope of Cattedown, 60 to 70 feet above datum, in pebbles ranging from 3 lbs. in weight to a quarter ounce and under. Contains inter alia cream-coloured granular felsite: red-brown porphyritic felsite, with blebs of quartz and imperfect felspar crystals; schorlaceous pegmatite; fine-grained granitoid rock with black mica and porphyritic quartz: coarse-grained rock of similar type but more nearly approaching granite. Among their associates were pebbles of volcanic grit, and hypersthene- and augiteandesite, not now found in the county in situ; and the first of the three quite novel and unique.

Chagford-Red: fine even-textured sub-crystalline schorlaceous pegmatite.

Chagford-Brown: medium-texture crystalline granular pegmatite. Chagford-Dark grey fine-grained aggregate of black mica and quartz, forming segregation in granite (called "pigs' eggs West Cornwall.)

Chagford-Pink and black: a well developed luxulyanite with a little quartz and some ferruginous decomposition products. Clazy well Pool (Meavy Valley) near-Red and dark grey junction of a red pegmatite, in which the felspar base is curiously speckled with more or less rounded granules of quartz and schorl associated with a porphyritic felspar; and a grey chiefly quartzose pegmatite thickly sprinkled with minute specks of schorl; there is a pinkish intermediate tinge.

Clazy well (ditto)-Grey: fine-granular mixture of felspar and quartz sprinkled with fine needles of schorl; a little mica. Collard Tor (near)-Red, weathering to pale pink: vitreous felsite weathering to earthy, with a few small granules and pyramidal crystals of quartz (the disappearance of some of which have left cavities) and light patches where crystallisation has begun in the felspathic base.

Colwell (Egg Buckland)-Brownish-grey: finely-granular felsite, with occasional small bleb of quartz or fleck of white mica; interpenetrated by dendritic markings from some of the joint faces. This is another exposure of the Cann elvan.

Cornwood-Bright red massive and sub-crystalline felspathic base, with a little quartz and casual schorl.

Cornwood-Pink: schorlaceous pegmatite, rather coarse texture, with porphyritic development of quartz.

Cornwood-Greenish-grey

schorlaceous greisen with extreme development of mica, a little kaolin. Cosdon Beacon (near summit)-Darkish grey: chiefly a fine-textured granite with abundant black mica, a slight porphyritic tendency; schorl in segregative crystalline nests, in the centre of somewhat coarser aggregates of quartz and felspar, with ferruginous staining, from which the mica has disappeared.

Cosdon Beacon (near Sticklepath)-Dull crimson: vitreous felstone, mainly a massive felspar with a little free quartz, and schorl casually disseminated and in strings; weathers to a whitish chalky

crust.

Dart (East, near Dartmeet)-Reddish-brown: fine-grained schorlaceous pegmatite with porphyritic felspars.

Dart (ditto)-Coarsely-granular mixture of quartz, schorl, felspar; the latter occasionally crystalline and partially kaolinised. Dart (ditto)-Red: mainly massive felspar with quartz and schorl.

Dart (ditto)-Light brown: fine-textured granular schorlaceous pegmatite.

Dart (ditto)-Brownish-grey: fine-grained granite, with black mica very closely and evenly distributed in minute black specks. Dart (ditto)-Pinkish-grey: a crystalline pegmatite of fairly even texture with a few porphyritic felspars and plates of black mica. Dart (ditto)-Grey an even-textured pegmatite weathering redbrown; a little schorl, mica casual and scarce.

Dart (ditto).-Cream-colour: schorlaceous pegmatite; moderate grain.

Dart (ditto).-Dull pink: matrix felspar and schorl with abundant irregularity; porphyritic quartz.

Dartmeet (East Dart). Grey: porphyritic felsite with very fine even-textured granular base of quartz, felspar, and black mica; porphyritic quartz in blebs and corroded grains; well-formed kaolinised crystals of felspar; black mica in hexagonal plates. Dartmeet.-Red to grey jaspideous vein in granite, containing fragments of quartz and felspar and some mica.

Dartmoor (locality unknown).—Varied rich red and black: one of the most distinctive of the Dartmoor rocks, unfortunately not found in situ; mainly felspar and schorl with a smaller content of quartz felspar red, of various shades, occasionally striped and mottled-some massive, other part crystalline, the crystals ranging to over an inch in length, a little kaolinization; schorl, mostly massive.

Dartmoor (locality unknown)-Dark reddish-grey: a fine-grained quartzose and schorlaceous granite with interstitial ferruginous

matter.

Devil's Bridge (near Princetown).-White: mainly crystallinegranular felspar and quartz, studded with little prisms of schorl; mica casual. Ditsworthy, near (Plym Valley).-Red: vitreous and granular felsite developing porphyritic felspars and quartz; a little schorl; a cavity from which a felspar crystal has disappeared contains acicular schorl (achroite) and fluor spar.

Ditsworthy.-Pale-red: giant granite, massive felspar with quartz and white mica; occasional felspar crystals.

Ditsworthy.-Red: schorlaceous pegmatite with porphyritic felspars.

Ditsworthy.-Dull buff: schorlaceous pegmatite, mainly felspathic, the peculiarity of which is that the schorl to a large extent outlines and isolates the irregular felspar granules.

Ditsworthy.-Dark red: a coarse irregular aggregate, mainly of felspar, quartz, and mica; the two former porphyritic, and the latter the predominant mineral in what may be regarded as a fine-grained interstitial granite; quartz small in quantity; felspar predominant; some of the felspar crystals over an inch in length; mica both black and white.

Ditsworthy.-Dark reddish-brown: less porphyritic variety of above; basal granite more defined and quartzose.

Ditsworthy.-Dull red: this would be taken for a compact red felsite, with veins of quartz and schorl and an occasional sprinkling of the last mineral; its occurrence in the field, however, shows it to be simply a highly altered slate; fused by the granite and almost wholly reconstituted. A similar rock occurs opposite the Dewerstone at Shaugh. They are mentioned here to show both the extent to which alteration may be carried, and the possible origin of some of the felsitic material.

Erme Valley (near Harford).-Junction of red pegmatite containing porphyritic felspars and quartz blebs, with dark grey schorlite, including pink porphyritic felspars. The felspar of the base in the one is apparently replaced by the schorl of the other.

Erme Valley (above Harford).- Cream: partially kaolinized felspar; irregular quartz; schorl; a little black mica.

Erme Valley (ditto).—Pale pink: slightly schorlaceous pegmatite. Erme Valley (ditto).-Pink: a somewhat coarse-textured granularcrystalline pegmatite with a small quantity of schorl.

Eylesborough (on Plym).-Pinkish-grey: coarse mixture of quartz and felspar with little schorl; felspars-some pale and kaolinised, others fresh and bright pink.

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Eylesborough-Light red coarse sub-crystalline schorlaceous pegmatite with quartz-veins and occasional porphyritic felspars.