436 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



which have been discussed in some detail in the foregoing descriptions, 

 are all that were sent home in the collections, though this was a very 

 common species in several localities where the work of the expeditions 

 was prosecuted. But even this meagre material gives much ground for 

 reflection and suggests possibilities in the way of alliance between the form 

 under consideration and the allied species known as magellauica. The 

 two forms are almost alike in size ; the males differ chiefly in the amount 

 of black barring on the lower surface ; the tail in the male sex offers a 

 diagnostic difference in that that of niagcllauica is bordered with white rec- 

 trices, the center ones being dark ; while the tail oiinornata in the adult male 

 is wholly dark, with no relieving outer rectrices. The females differ more 

 than do the males, if the lead-colored head and neck of iiionmta is an un- 

 varying characteristic. For even in the small series dealt with the two 

 males, which can only be referred to this form, vary in the direction of 

 niagelianica, one, 7818, having a white external tail feather on one side of 

 the tail, and the other having the lower tail-coverts pure white. Moreover 

 in a large series of birds, only to be considered as true magellanica, the 

 number of bordering white rectrices is quite variable, and consequently the 

 number of dark rectrices varies also. The normal number, fourteen in 

 this genus, is arranged, so far as color is concerned, in ever differing pro- 

 portions, but is usually symmetrical. Thus the tail of the bird used by 

 Count Salvadori in his description had but the four central feathers greyish 

 black (see Cat. Birds Brit. Mus. XXVII, p. 133, near the bottom), while 

 the bird used in this work has but the two outer rectrices on either side 

 white. Consequently, there may be ten black feathers in the tail of a given 

 individual of ;;/(7^^//rt';//(rrt' with four white ones, or ten white ones with four 

 black ones, and a consistent symmetrical variation is to be expected between 

 these two extremes. The recent close relationship between the two species, 

 magellauica and inoruata, is perfectly evident from what has been presented, 

 and it is of further interest to consider that the extremes now seem to have 

 some difference in their geographical range ; for while the two species both 

 occur and both breed in the Straits of Magellan region, yet, on the whole, 

 mornata is a western form of a recently separated species and conversely 

 magellanica is an eastern form as now existing. There are fifteen magellanica 

 in the series of skins in the British Museum and five of these, one third, 

 are from the Falkland Islands ; there are six birds in the inornata series, 

 five of which are from Chili and one from the Straits of Magellan. 



