82 Rev. H. B. Tristram on the Ornithology of Northern Africa. 



164. Erismatura mersa. (White-headed Duck.) 



lu the lake of Bou Guizauo, June 1856 ; Tuggurt, December 

 1856. 



165. Gelochelidon anglica. (Gull-billed Tern.) 

 Occurs in flocks both in the Western and Eastern Sahara. 



Several shot at Bou Guizouu^ and near A'in el Ibel, on the El 

 Aghouat route, and vast flocks met with round the Zahrez, in 

 the same country. We found it also breeding at Zana the fol- 

 lowing spring. 



166. Sterna minuta. (Least Tern.) 

 Occurred at Bou Guizoun. Not plentiful. 



167. Hydrochelidon nigra. (Black Tern.) 



Resorts to various salt-lakes. I only met with it in the 

 Western Sahara. 



168. Hydrochelidon leucoptera. (White-winged Black 

 Tern.) 



More widely distributed than the last-named. 



169. Hydrochelidon hybrida. (Whiskered Tern.) 

 Abundant on most of the salt-lakes, but never observed in 



company with the H. leucoptera. It is in the habit of following 

 the labourers in the oases in tffe barley patches in pursuit of 

 insects. 



170. PoDiCEPS CRisTATUS. (Great Crested Grebe.) 

 Observed once at Tuggurt. Apparently only a solitary 



straggler. 



171. PoDiCEPS AURiTUS. (Eared Grebe.) 

 In the lakes of the Wed R^hir. 



173. PoDiCEPs minor. (Little Grebe.) 

 Common in the Northern Sahara. 



None of the Grebes were noted by me in the South, even in 

 the most suitable localities. 



I here conclude my catalogue of the birds of the Sahara ; and 

 though I fear the readers of 'The Ibis ' will have found my long- 

 drawn story as dry as the desert which has produced it, I can- 

 not presume to think that it is by any means complete. I have 



