170 THE BIRDS OF MONGOLIA ETC. 



46. LocusTELLA CERTHiOLA, Pall. Camishevka priatUvaya. 



Is tolerably abundant in the Hoang-ho valley, but is very rare at 

 Ala-shan and Halha, inhabiting only small clear marshes. We did not 

 obtain it more than once in Kan-su. It is extremely common in Ussuri 

 country. On the coasts of the Japanese Sea I observed the species migrating 

 in the early part of October. 



47. Sylvia curruca. Lath. Slavka peresmeshka. 



By no means scarce in S.E. Mongolia, the Hoang-ho valley, and the 

 plains of Ala-shan, where it inhabits the sacsaulnic thickets. In the Ala-shan 

 and Kan-su mountains we did not meet with a single specimen. The first 

 birds arrived in the Hoang-ho valley about the commencement of May, when 

 the males begin singing, frequently flying up into the air from thirty to forty 

 feet ; and then, vibrating with their wings, they slowly descend on bushes or 

 small trees. This strange performance I have observed at home executed 

 by S, cinerea, but not by S. curruca. 



48. Sylvia aralensis, Eversm. Slavka aralskaya. 



We observed it only in the bush-covered Ala-shan plains, in pairs and 

 single specimens, but even there very scarce. In the latter part of May we 

 found a nest in a small hole of a clayey cliff. It was built very carelessly, 

 and without any lining, and contained two quite fresh eggs, of a rather large 

 size; they measure 0'''75 and 0'''61 in their respective diameters, are of a 

 rounded conical shape, of a light blue colour, marked with small reddish 

 spots, which form a sort of ring at the larger end of the egg. 



We did not find this species anywhere else ; and its northern limit of 

 distribution seems to be formed by the southern portion of Gobi, whilst the 

 eastern is formed in Ordos by the edge of the desert. 



