110 



and reefs exist ; occasionally wandering to Maine in North America, 

 and to Europe, even as far as England. Almost unknown on the 

 South American side of the Pacific ; otherwise very generally dis- 

 tributed. 



This and the two preceding species form a very natural group, 

 diifering from the other Sea-Terns in several points ; for instance, 

 only one egg is incubated at a time. But with every desire to 

 separate them generically, I am unable to find any structural 

 differences which would warrant such a proceeding. 



a. Ad. st. 

 h,e. Ad. st. 



d-n. Ad. sk. 



0. S ad. sk. 

 p. (S ad. sk. 



q. Ad. sk. 



r. (S ad. sk. 

 s. Juv. sk. 

 t. Ad. sk. 



u, V. Pull. ; tv, 

 .V. Juv. ; y. 

 Ad. sk. 



z. 2 ad. sk. 



a. Ad. sk. 

 b'. Vix ad. sk. 

 c'. Juv. sk. 

 d'. Ad. sk. 

 e',f'. Ad. sk. 



ff'. Ad. sk. 



h'. 2 "d. sk. 



i'-s'. 6 2 ad. ; 

 t'. Juv. ; u', 

 v. Pull. sk. 



w'. Vix ad. sk. 



x. 6 juv. sk. 



y', Juv. sk. 



z . <S vix ad. 



a". Vix ad. sk. 



b",c". Ad. St. 



d". Ad. St. 

 e" . Juv. sk. 



/",//'. Pull.; 

 h", i". Juv. St. 



North America. 

 North America. 



Corpus Christi Pass, Texas, 



May {F. B. Annstrong). 

 Veragua {Arce). 

 Southern Water Cay, Brit. 



Honduras, May (O. (S'.). 

 Mazatlan, W. Mexico, Dec. 



(A.Forrev). 

 Panama {McLeannan). 

 Mouth of the Amazons. 

 Fernando Noronha I., Sept. 



(H. M. Harrkon, R.N.). 

 Ascension Island, Dec. {Lt. 



Mount joy Sqtdre, Il.N., Sf 



Prof. D. Gill). 

 Ascension Id., April 4, 1873. 



Fernando Po, W. Africa. 



Madagascar [Margastre). 



Madagascar. 



Mauritius (C E. Bexvsher). 



I. of Rodriguez {Eev. H. H. 



Slater). 

 I. of Piodriguez. 

 Seychelle Is. 

 Laccadive Is., Feb. {A.O. II.). 



Ceylon, June ( W. V. Legge). 

 Pegu, June. 



Tonghoo {Capt. Lloyd). 

 Duke of York Id. 



?Duke of York Id. [Rev. 



G. Browti). 

 Australia. 



Australia. 



Houtman's Abrolhos, W. Aus- 

 tralia, Feb. 1843 [Gilbert ^• 

 Gould). 



Houtman's Abrolhos, Jan. 

 1843 (Gilbert). 



Purchased. 

 H.R.H. Duke of 



Sussex [P.]. 

 Salvin-Godman Coll. 



Salvin-Godman Coll. 

 Salvin-Godman CoU. 



Salvin-Godman Coll. 



Salvin-Godman Coll. 

 H. Saunders Coll. 

 H. Saunders Coll. 



H. Saunders Coll. 



H.M.S. 'Challenger' 



Exp. 

 L. Eraser Coll. 

 Shelley Coll. 

 Capt. Bewsher [C.l. 

 Shelley Coll. 

 Transit of Venus 



Expedition. 

 Sir John Kirk [P.]. 

 Shelley Coll. 

 Hume Coll. 



Hume Coll. 



E.W. Gates, Esq.[C.]. 

 Tweeddale Coll. 

 Eev. G. Brown [C.]. 



Tweeddale CoU. 



Sir Thos. Mitchell 



[P.]. 

 J. Gould, Esq. [P.]. 

 H. Saunders Coll. 



Gould Coll. 



