1920.] Letters, Extracts, and Notes. 319 



mostly in regcird to their distinctive characteristics. From 

 an oological ]joint oi' view, I consider them not only dis- 

 tinctive bnt absolutely unique, mainly because the whole of 

 the pigment lies beneatli the outermost lime layer. In the 

 type egg this is most constant, and even tiiose markings 

 which at first sight appear to be on the surface, I find, on a 

 closer examination, are really beneath the gloss or glutinous 

 hayer. 



In the series which I exhibit there are one or two eggs 

 witii brownish markings which appear I0 be on the surface, 

 but these I attribute to nest stains. 



Lechner in ' Oologia Neerlandica' calls attention to 

 similar ciiaracteristics in the eggs of the Common AVhite- 

 throat (Sylvia communis) ; I consider, however, that a 

 certain form (i.e. the marbled form of tlie Nightjar, Copri- 

 mulyus europaus) shows, oologically, certain well pronounced 

 similar characteristics, as may be seen by the eggs of that 

 species exhibited for comparison. The texture of the shells 

 is also distinctive ; some have the appearance of being- 

 corrugated ; the pittings lie very deep and widely apart. 



British Museum Expeditions, 



Mr. Willoughby P. Lowe left England on the 14th of 

 November last on an important expedition to the West 

 Coast of Africa on belialf of the British iNIuseum (Natural 

 History). He will be the guest of Captain Dane, R.N., 

 who, in the interests of scientific exploration, most generously 

 invited Mr. Lowe to accompany him as naturalist on 

 H.M.S. ' Dwarf ' — of Cameroon fame. Mr. Lowe proceeded 

 to Lagos in Southern Nigeria, and, while waiting to pick 

 up the cruiser, will form a collection of birds in the 

 neighbourhood. 



On joining the 'Dwarf/ he will have an opportunity of 

 visiting numerous localities on the AVest Coast, and hopes 

 to pay particular attention to Gaboon and the Rio Muni 

 and to visit the rivers Aloonda, Camma, Agowe, and Muni — 

 the type locality of many of Du Chaillu's birds described by 

 Cass^n. A special attempt will be made to obtain specimens 



