DISTBIBUTION OF THE GULLS AND TEEXS. 



405 



Noddy, A. stoJidiis, was also found. These two species make a sub- 

 stantial nest of seaweed, and place them on trees, bushes, and rocks. 

 Of A. fenuirostris (Temm.), I can only say that it seems to have 

 been obtained at Senegal, the islands of Rodriguez and Mauritius, 

 and the west coast of Australia : it differs from A. melanogenys in 

 having grey lores and face ; but much more information is requi- 

 site respecting it before its range can be mapped out with any 

 approach to accuracy. 



Of the Skimmers {BhyncJiopsince) ^ which have the general ap- 

 pearance of Terns with a remarkable projecting under mandible, 

 there are three species separable by their plumage alone. In 

 habits and nidification they are alike, frequenting the banks of 

 large rivers, and depositing their eggs on the sand. The most 

 distinct is naturally R. nigra of Tropical America ; M.Jtavirostris 

 of Egypt and the Bed Sea, and B. alhicollis of India, being more 

 closely related. The American species ranges from New Jersey, 

 along both sides of America down to 45° S. lat., and its complete 

 isolation from its two close allies is very peculiar. 



It is, then, in the North Pacific that we find the majority of 

 the typical Larince, and it is there alone that the Arctic and 

 white-primaried forms are connected through L. glaucescens with 

 the group which have distinctly barred primaries, almost all the 

 members of which are also found there. It is only in the North 

 Pacific that we can see w^here the three-toed Bissa began to 

 deviate from the typical four-toed Gulls, and it is only there that 

 a faint line of connexion can be traced between the only two 

 species which have forked tails {Xema). It is only along the Pacific 

 coasts that the continuous chain can be followed with the typical 

 Hooded Gulls, of which L. ridihundus is the Palsearctic representa- 

 tive, and which in L. glaucodes red^chQ^, unbroken to the Straits of 

 Magellan, whilst in the eastern hemisphere it cannot (with the 

 solitary exception of the South-African L. phceocepJialus) be found 

 south of 10° N. lat. It is again only in the North Pacific that we 

 find the peculiarly-coloured tern Sterna aleutica, which so clearly 

 connects the typical Sternce with the intertropical Sooty Terns, 

 S. lunata, S. ancestheta, and 8. fuliginosa. It is not necessary to 

 lay much stress upon those Pacific gulls which, with slight modi- 

 fications, have barred tails at all ages and a hood in the immature 

 stage, for there the chain is more broken; and the majority of the 

 SternincB are also so wide-ranging that their distribution teaches 



