1876.] 



MR. H, SAUNDERS ON THE STERNIN.E. 



665 



Haliplana discolor, Coues, Ibis, 1864, p. 392; Elliot, B. N. Am. 

 ii. pi. 57(1869). 



1 Hydrochelidon somalensis, Heugl. Orn. N.O.-Afr. p. 1458, 

 p. ccvii (1873). 



Haliplana anosthcetus, Gray, Hand-list, iii. p. 122(1871). 



Sterna melanoptera, Swainson, B. W. Afr. ii. p. 249 (1837) 

 (type in Camb. Mus. examined, H. S.). 



This species, originally described from the Philippine Islands, is 

 somewhat smaller than S. fuliginosa ; the colour of the mantle is 

 also less intensely dark. But the principal distinction is found in 

 the feet, in which the webbing, instead of coming down to the claws 

 between the outer and middle toe as in S. fuliginosa, only descends 

 to the last joint, showing a more important structural difference 

 between two such closely allied species than there is between Ony- 

 choprion and typical Sterna — an additional reason for discarding the 

 former genus and its synonyms. The drawings show the shape of 

 the feet in both species. 



Fig. 2. 



Fig. 3. 



Fig. 2. Foot of Sterna fuliginosa. Fig. 3. Foot of Sterna ancestheta. 



In the young of the present species the underparts are light- 

 coloured on emerging from the downy stage, whereas in S. fuliginosa 

 they remain dark for some time. 



Its range appears to be nearly identical with that of S. fuliginosa, 

 and is noticed under that head. 



Sterna lunata, Peale. 



Sterna lunata, Peale, U.S. Expl. Exp., Birds, p. 277 (1848) ; 

 Cassin, U.S. Expl. Exp., Birds, p. 382 (1858) ; Schlegel, Mus. P.- 



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