130 TT.S. NATIONAL MUSEUM BULLETIN 223 



Australia), however, apparently no measurements or descriptions of 

 the egg or eggs have been recorded. 



I discard as erroneous the eggs attributed to the shafttail by- 

 Carlisle (1923, p. 122), who reported nests and whole clutches of 

 eggs of this bird. 



Nothing is known as to the number of eggs laid by one hen in one 

 season, the interval between eggs, the existence or otherwise of host 

 specificity, the length of the incubation period, or whether or not 

 the laying bird removes one of the host's eggs at the time of depositing 

 her own. Probably only one egg is laid in any one nest. 



Hosts 



Mors, (1925),R.Neunzig (1929b), and A. Roberts (1939) stated that 

 the violet-eared waxbill, Granatina granatina, is the main host of the 

 shafttail. It is true that there are more records of this waxbill serving 

 as a victun than there are of any other single host species, but that sLx 

 other species are also known to be affected and that the records for 

 Granatina total less than half of all the cases of host-parasite relations 

 make it unwise to emphasize this one host species unduly. All but 

 one of the recorded hosts are weaverbirds, and it does seem probable 

 that birds of this family are the chief victims of the shafttail; however, 

 with the present state of our knowledge, this generalization is tenuous. 

 The known hosts and the data for each follow. 



Black -chested longtail: Prinia flavicans (Vieillot) ^^ 



About sunrise on January 1, 1925, in the bushveldt between Pietpot- 

 gietersrust and Moorddrift, Transvaal, I found a nest of this warbler 

 containing three eggs of the owner. About a quarter of an hour later 

 I passed near it and saw a female shafttail fly out from it and go over 

 to a male of its species about 100 feet away. The two then flew off. 

 On examining the nest I found, in addition to the three Prinia eggs, a 

 fresh, pure white one, similar in size and shape to the egg of the pintail. 

 I consider that the egg was laid by the shafttail, even though it cannot 

 be ruled out that a female pintail might have laid the egg during the 

 15 minutes between my visits. The pintail was present in the region. 

 Unfortunately, in the excitement over this discovery, I took the eggs 

 out of the nest to look at them more carefully, and while I was examin- 

 ing them, the host returned and then flew off. I put the eggs back, 

 but she deserted the nest. 



The parasitic egg was very slightly larger than those of the host, 

 and measured 16.3 by 12.5 mm., as compared with 16 by 11.5 mm. of 

 the host. The parasitic egg was unmarked white, while those of the 

 host were pale olive green marked with brownish lines and spots. 



" Salvia flavicans Vieillot, Encyclopfidie mfithodlque . . . , vol. 2, 1820, p. 438 (South Africa, Namaqua- 

 land ex Levalllant). 



