from the Baltic, and bodily passed over the whole of Scotland, Western Islands and all, after filling up the Minch-slipping over the whole land like the bedclothes slipping over a sleeping man. This theory admits of the after-effects of local glaciers-the dwindling residues of the enormous mass.

The second theory is based upon the Gulf Stream having at one period pursued a directly northern course, up the depressed valley of the Mississippi, and down the Mackenzie River, so as to impinge upon Banks' land, and, by the genial influence of its tepid waters, supply the necessary warmth to the plants which furnished the coal which there occurs. Then the cold current from Baffin's Bay and the North would bear a great ice sheet to grind and tear itself against our western shores-bear off their shattered fragments upon its flanks and shoulders-carry them in its onward course up and among the fiords and passes of our hills and valleys, shedding its burden from off the fringes of its shrivelling bulk.

The third theory differs not widely from the last, but regards the greater amount of the ice work of the central heights as having been effected by material of home growth. Maintains that the absence of the heating Gulf Stream from our western shores had given us the climate normal to our latitude, namely, that of Labrador. That our hills supplied the néré which formed our native glaciers, which passed naturally and normally down every valley which radiated from the central parent-height. But that simultaneously, or upon an after-depression of the land, ice-floes were borne from the north and west; and, pressed by the vis a tergo of a continually advancing sheet, slid over the lower grounds, or the sinking landaccounting for the more general but less profound action which is there disclosed.

It is to be noted, that each of the three theories alike puts the question-In what direction did the ice pass over the western shores? The first theory demands that it passed from east to west, both of the others that it passed from north-west to south-east.

It must also be noted that the Shiant Islands, situated midway in the passage of the Minch, occupy a very crucial position for the determination of the problem, so far as the west side of the country is concerned. If foreign rock fragments are found upon these islands, they must lie upon its western shores, and be of the rocks of the Long Island, if the ice came from the west;-they must lie

upon its eastern shore, and be of the rocks of the Mainland, if it came from the east. If the ice-flow was from the west, the smoothing and the polishing must be seen upon the western shore of the islands, the eastern being rough and craggy; and vice versâ as regards both, if the Baltic flow reached thus far from the east.

Upon the western shores of the Shiant Islands there lie numerous foreign blocks of stone. These blocks of stone are the rocks of the

Long Island.

The Shiant Isles show rounded and polished contours upon the west, and rough and craggy forms upon the east.

The whole evidence which the Shiants afford is thus directly in favour of a trend from the west, and altogether negatives one from the east.

There are two spots where

To particularise more in detail. foreign blocks are to be found in moderate amount. The first is the low boulder-spit, which connects the two westerly islands. Upon the west side of this spit, from near its summit-level down to low-water mark, there are to be found many pieces of that close-veined variety of hornblendic gneiss which is common. in Harris and North Uist, but which the writer does not remember to have seen of exactly the same character, on the mainland of Scotland-while the nearest locality of hornblendic gneiss on the mainland is not to the east of the Shiants, but far off to the northnorth-east. Along with this gneiss some pieces of Cambrian grit are to be found. A very few of the latter are also to be found on the east side of the spit, but these were so small in size, and lay so near the top of its slope, that there can be little doubt that they had been thrown over by the waves in storm. Upon the north-west shore of the eastern horn of Garabh Eilan numerous pieces of the same Cambrian grit were found, and these were all of that yellow-spotted variety which occurs, and, so far as the writer is aware, alone occurs on the opposite shores of the Peninsula of Lewis.

Both Eilan an Tigh and Garabh Eilan are rounded and hummocked: from the west in the case of the former, from the south-west in the case of the latter. Eilan Whirry is not hummocked at all. The two first-named islands form with one another almost a right-angle on the west. An ice sheet which had passed either through the Sound of Harris, or through the deep trench at Tarbert (and ico

has passed through that trench from the west, as shown by striation, and the carry of boulders) would, after having been temporarily embayed in the angle between the islands, pass over them to fall over their high eastern cliffs into the sound between them and Eilan Whirry, as a shattered mass of fragments, powerless in any way to affect the eastern island, and which must have been merely hurried grinding past its shores.

A line of fragments disposed in close sequence to the east of a gap of rock near the summit of Eilan an Tigh shows very clearly the direction of the flow. Several large boulders lie upon the high western flanks of Garabh Eilan, but these are of the rock of the island, and the positions in which they lie, though they are true let-down boulders, did not seem to disclose anything definite as to their past.

VII.

NATURAL HISTORY NOTES.

BY FRANK NORGATE.

(Communicated by the Honorary Secretary.)

Read 30th December, 1879.

NESTING HABITS OF THE CARRION CROW. This bird is common in the neighbourhood of Sparham in the summer, nesting every year in Foxley Wood in considerable numbers. I seldom see them in the winter, but on the 1st of February I saw one flying near Foxley Wood. These Crows seem to be on very good terms with the Kestrels, as I frequently find a Carrion Crow sitting on its nest in one tree, and a Kestrel on its nest in the next tree, within a yard or two of the Crow. Once or twice I have been able to count the eggs in both nests at once, by climbing up a little higher than the nests. I often find two or three clutches of Crows' eggs in one day, and as many again the next day.

On the 10th of May, 1878, I counted twelve or fourteen Carrion Crows as they flew out of one oak tree in the wood, and on the 29th I saw about twenty fly out of an oak (or rather a clump of three oaks standing close together). I counted seventeen of these Crows but could not count them all. Several which croaked were certainly Carrion Crows, and as I heard no Rooks I have no doubt they were all Carrion Crows.

The same nests seem to be often used alternately by Crows and Kestrels. All the trees (except one) in Foxley Wood are oaks.

In some meadows outside the Wood are many very tall grey poplar, ash, and elm trees, and a few years ago there was a gigantic oak in which I saw three nests at once, but only one had eggs in it. In these meadows I once sat on a gate-post and counted fourteen nests, one or two were Kestrels', the rest were Carrion Crows', but they were not all in use at the time.

Two of

I have reason to believe that a Carrion Crow laid five clutches of five and four eggs in each clutch in about ten weeks. these later clutches had a very small egg in each.

I have never seen more than five eggs in a clutch, and Carrion Crows frequently sit on only three eggs, as Rooks do also. When a Crow nests on a tree in an open meadow, she generally sits so close that one may strike the tree-trunk a good blow or two with a heavy stick ere she will leave the nest.

The Crows which nest in the wood are so very shy that I can seldom go near enough to see them fly from the nests. These tactics are about equally good in both cases, because, in the thick wood the bird can leave the nest without being seen, but in the open field the safety of the nest depends upon the bird sitting as close as is possible.

Carrion Crows also nest in Sparham Wood, and two or three other small woods near Foxley.

APAMEA OPHIOGRAMMA. I took three specimens of this moth at light in a marsh at Dilham, in Norfolk, about the middle of August, 1879.

SUPPOSED OCCURRENCE OF TRIPHÆNA SUBSEQUA IN NORFOLK. In September, 1878, I took many specimens of the common Triphana orbona (as I then thought) at sugar, in Sparham. In October I spent a week in Bedfordshire sugaring for Xylina semibrunnea, and devoted one day to pupa-digging in Yardley Chase,

Northamptonshire. I do not remember taking any T. orbʊna or T. subsequa whilst I was away from home, except one orbona at East Dereham, Norfolk. On looking over my captures some time afterwards, I was delighted to find that one supposed orbona is really subsequa. I feel quite sure that I took it in September, at sugar, in Sparham, mistaking it for T. orbona, but there is just the possibility that I reared it from a Yardley Chase pupa. I feel sure, however, that I never did in my life rear any of the Triphane, except (several years ago) a few pronuba and one fimbria.

I had but one specimen of T. subsequa in my collection, and have since taken one other in Ramnor Wood in the New Forest, in September, 1879.

EUPHORBIA ESULA IN NORFOLK. There is in Sparham a large bed of this plant covering several yards of a hedge bank. I have known it here (by sight, though not by name) for about thirty years past. Last June I gathered a bit and identified it. I have no reason to think it has been introduced to Sparham, unless by accident with other seeds, in the course of farming operations.

PACHYPROTASIS LEVICOLLIS. On the 6th of June, 1879, at Hockering, Mr. H. Howard, who was with me, bottled for me a beautiful fly, which Mr. Bridgman identified by the above name and considered it a good "find."

On the 23rd of June, 1879, in Sparham, I found three larvæ of Porthesia chrysorrhea feeding on a blackthorn fence. I reared them all.

ORTHAGORISCUS MOLA (THE SHORT SUNFISH). On the 19th of November, 1879, on the Salthouse Marsh, Mr. J. H. Gurney, jun. and I noticed the remains of a large fish which puzzled us, until the fisherman who was with us described it as a "Sunfish," and said it was about "five feet six inches deep across the two flippers," and not so long from head to tail. We saw the mouth and one eye, but the fish had been boiled and mauled so that it was difficult to recognise it. Brett, the captor, told me he found it washed ashore on the 31st of last month, that he rove a line through a hole which he cut in one of the flippers, and towed the fish behind his boat, but that as soon as he set sail the sunfish revived and pulled the boat round once or twice, much to the consternation of another man who was in the boat at the time. From what I saw and heard I am sure this was the short Sunfish, not the oblong one.