URIA TROILE. Common Guillemot. Colymbus troile, Linn. Faun. Suec., p. 52. Uria troile, Lath. Ind. Orn., vol. ii. p. 796. leucophthalmos, Fabr. Prodr., p. 42. —— rmgua, Brinn. Orn. Bor., p. 27. —— hringvia, Keys. & Blas. Wirbelth. Eur., p. 93. ——— lacrymans, Valenc. Voy. de la Chloris, pl. 23. —— troile leucophthalmos, Schleg. Rev. Crit. des Ois. d’Eur., p. 107. —— minor, Steph. Cont. Shaw’s Gen. Zool., vol. xii. p. 246, pl. 63. norwegica, Brehm, Vig. Deutschl., p. 933. —— leucopsis, Brehm, ibid., p. 982. alga, Brinn. Orn. Bor., p. 28. A momEnt’s reflection only is necessary to convince the lover of nature that the creatures inhabiting the great waters are as numerous and as varied in their forms as those dwelling on the land, and that, were the mighty deep to unfold to us the whole of its treasures, we should find that they comprise objects of beauty and colouring as numerous, if not more so, as those of the air. Among aquatic birds, two very extensive families are found to exist preeminently fitted to frequent the face of the ocean, namely the Petrels and the Auks. The greater number of the former inhabit the seas south of the equator, as the latter do almost exclusively those north of it. The members of the Procellariide, or Petrels, feed principally on the lower _ Physalia, and the Alcide or Auks on the smaller fishes ; by which means the balance of animal life is main- tained, and probably ever will be so, as long as Nature’s laws are not interfered with by man. To ruthlessly kill the oceanic birds when they seek our rock-bound islands for the purpose of reproduction is surely a mistake ; for the result would be an excess of such fishes as the herring, the mackerel, and the pilchard, upon the fry of which most of our sea-birds feed ; and such an excess would probably be accompanied by diseases such as sometimes occur among our birds and quadrupeds when redundant in number. These observations may appear trivial; but I have penned them as they occurred to me when sitting down to write the history of the Common Guillemot, numerically perhaps the most abundant member of its family, if not of the whole of our sea-birds. In a broad sense, I may say that this well-known bird is strictly confined to the northern hemisphere, where its range extends from the borders of the Arctic circle to the latitude of Madeira and the Azores. Always at sea during the months of autumn and winter, it dwells day and night on the face of the water, seldom flying unless from one part of its fishing-bank to another. On the commencement of spring the promptings of nature induce it to approach the land and resort to those coasts whose rocky precipices afford a resting-place for its large singularly formed egg. Some time after incubation has been effected, the parent takes its young down to the sea, sheltered bays and more quiet firths being then resorted to, such situations appearing to afford a certain degree of protection to the young until they have acquired sufficient power to enable them to proceed to the open waters destined for their future abiding-place. In the comparatively little-disturbed waters alluded to, the fry of the herring, the pilchard, the sprat, and other fishes are found, the whole affording an abundant supply of nutriment to the birds both old and young. To enumerate individually the breeding-places of the Guillemot in the British Islands is quite unnecessary, since they are to be found from the Land’s End, in Cornwall, to the coasts of Wales, to Yorkshire, to Ailsa Craig, the northern and other parts of Scotland, and the Hebrides. Similar situations of a favourable cha- racter in the sister kingdom of Ireland are all more or less resorted to by this bird, which, moreover, is equally numerous in all suitable localities in the northern portions of the continent of Europe and America. T have alluded to the immense numbers of this bird in all the localities frequented by it; and in illustration of this assertion, I cannot perhaps do better than give the following paragraph from an interesting paper by Mr. Robert Gray on Ailsa Craig and its inhabitants, published in the ‘Intellectual Observer,’ vol. iv. pe LS Sc. :— ; “The Guillemot and Razorbill breed on the narrow ledges of rock occupying the entire face of the highest precipices of Ailsa Crag, and presenting, when viewed from the sea, a veRy renanDe and orderly appearance, They make no nest, but lay their single egg upon the bare ledge, which is seldom more than six inches in breadth ; so that each bird is compelled to sit erect when incubating. I have frequently climbed to a height