DITBUN NATUBAL UX8T0BT SOCIETr. S7 



pletely deserted, and then, as it were, supposing, from the absence of their lar- 

 ger brethren, that they were more profitably engaged elsewhere, the other spe- 

 cies fly off to join the ilock. During the breeding season the herring-gull pos- 

 sesses a habit very similar to the rook — diving or falling through the air, and 

 turning over several times in its descent. This is frequently performed by 8e> 

 veral birds at the one time, and is accompanied by their peculiar laughing cry. 

 The presence of raptorial birds does not seem to occasion those birds the terror 

 that wo see manifested by others, as the peregrine (Falcoperegrinus) will fre- 

 quently glance past a flock without disturbing them from their avocation, or 

 the least outcry being raised against him. To one not versed in their habits, the 

 appearance of the peregrine at times would suggest difl^erent conclusions, as this 

 falcon chooses some commanding position along the precipice as a perching place, 

 where for hours he will maintain the same position, with the head inclined towards 

 the rocks, as if appearing to take an exceeding interest in the movements of the 



fulls drifting upon the wind below him like so many snow-white feathers. This 

 abit of the peregrine is, however, the mere listlessness of repose, and is gene- 

 rally indulged in after repletion. A single common gull, or kittiwake, flying 

 along the face of the precipice, invariably stoops downwards, or otherwise 

 avoids the vicinity of its suspicious foe. Familiar as ornithologists may be with 

 the appearance of the breeding haunts of the Laridoe, as observed in the full 

 glare of sunshine, there is yet another view possessing the most engrossing inte- 

 rest — the same haunts observed at night time, when we see the gulls appear 

 like so many snow-white ribbons wound round the rocks — the gigantic masses 

 of shade flung by the rock during moonlight, and the spectral forms of the gulls 

 wheeling upward from their nests, and again settling with their usual clamour. 

 At times the cormorants join their hoarse guttural croaking, whilst the booming 

 of the sea appears more audible and more solemn in the silence of the night. 

 Fearing that 1 am occupying too much of your valuable evening, I will hastily 

 conclude with a few observations respecting the probability of the masked gull 

 (Larus capistratus), and Bonaparte's gull (Larus Bonapartii), being confounded 

 with varieties of the black-headed gull (L. ridibundus). Without presuming 

 upon a subject which is difficult to decide without a large number of sjjecimens, 

 it is to be remembered the confusion of which the Laridsc were the subject until 

 the last few years, when critical examination and practical observation proved the 

 wagel (Larus no^vius) to be the Larus marinus in its plumage, the gray gull 

 (La Mouette grise) of Brisson to be the lesser black-backed gull in young plu- 

 mage, the winter gull to be Larus canus in its seasonal change, and the tar- 

 rock (Larus tridactylus) to be the immature kittiwake (L. rissa). It is also to 

 be recollected that there is no infallibility in classifying species, as we find au- 

 thorities as grave as Brisson and Storr agree upon the claims of Larus naevius 

 to be a distinct species from the adult bird. One claim advanced for Larus Bo- 

 napartii being a distinct species, appears to be its diminutive size, length of 

 wings in exceeding the tail some two inches, and the peculiar colour of the tarsi. 

 If such be the case, the specimen now before you is a just candidate for the ho- 

 nour, as this veritable black-headed gull possesses in an eminent degree the ne- 

 cessary qualifications, so much so that the wings give it the peculiar tern shape, 

 and actually exceed the tail by three inches and a half A bird in the first year's 

 plumage, also before you, you will find to be much larger in size, and possess 

 more of the acknowledfged character of Ridibundus. It might be supposed that 

 the increase of age might have a corresponding increase of size ; but, as vour 

 Honorary Secretary Justly observed in his paper, that "the examination ot nu- 

 merous specimens of Ridibundus has shown such differences in their relative 

 positions and size, that it would seem much dependence could not be placed on 

 measurements." If a standard is to be erected, and all birds adjudged specific 

 distinction on account of a difference in size, it is impossible to say how many 

 more species may be discovered in our Fauna. The colouring of the wing fea- 

 thers is also laid down as a characteristic of Larus Bonapartii ; but in the spe- 

 cimens of Ridibundus now before you, you will find all of them without difficulty. 



