of certain Birds in North-eastern Africa. 127 



The Arabian fishermen stated that the old birds cover the 

 young ones immediately after their being hatched. 



5. Sterna affinis, Riipp. (Plate V, figs. ], 2, 3.) 



This species and the following agree with the former in locality, 

 season, and other specialities of breeding, — being, however, much 

 less frequent. They also breed in companies on the shore, but 

 separately from each other and from S. senegalensis. 



The average dimensions of eight eggs, collected near Amarat 

 and on the island of Lobo (Archipelago of Dahalak), are 23 lines 

 by 16. The weight of the shell varies between 36 and 44 grains. 

 There are two principal varieties with respect to coloration : — [A) 

 white or greenish-white with coarse spots, sometimes scattered, 

 sometimes arranged in groups. The centre of each spot is violet- 

 grey or blackish-grey, which colour passes into a beautiful chest- 

 nut-brown and dark-brown towards the periphery ; the edges 

 are generally burnt-brown. These eggs resemble those of Cep- 

 phus grylle. (B) yellowish, sometimes with a reddish shade, 

 dotted and striolated ; the darkest points, dots, and streaks are 

 black-brown or brownish-red ; the mai'gins of the spots shining- 

 brown or I'ed. In one specimen bluish-grey spots form a zone 

 round the base with many flourishes. All the eggs, held against 

 a flame, are transparent yellowish-green. 



Some of the eggs much resemble those of Sterna cantiaca; 

 but they are all distinguished by the more variegated coloration, 

 the smaller size, and the different structure, characterized by 

 shallow, serrated pores, and by finely granulated rounded tuber- 

 cles, which render some parts of the shell rather rough. 



6. Sterna velox, Riipp. (Plate V. figs. 4, 5, 6, 7, 8.)* 

 Of this species, which has the same peculiarities of breeding 



as the preceding two, I have fourteen eggs in a good state of 

 preservation and five injured ones, collected on the island of 

 Lobo, the 1st of August, 1857. They are distinguished from 

 all the eggs of Sterna hitherto known, by their considerable 

 size and their beautiful and very variegated coloration. Their 



* This is the " Swift Tern " of British Lists, a specimen of it having been 

 once killed in Ireland, as mentioned in Thomjison's ' Birds of Ireland.' — Ed. 



