136 :\rr. p. R. Lowe on the 



have nothing to do with seasonal change. Moreover, these 

 distinctive phases are distinguishable in the young in down. 

 For instance, ]\Ir. Grant showed me two young, said to be 

 eight weeks old, taken by Mr. Bennett from the same 

 colony on the South Orkneys, which are especially inter- 

 esting, one being pure white (both as regards neossoptyles 

 and teleoptiles) and the other dark slaty-grey — the grey in 

 this case also affecting both tlie down-feathers and the 

 con tour- feathers, which had already come through, although 

 the down-feathers were not so dark as these latter. 



IV. Genera and Species of Chionidida. 



A. Chionis Forster, Enchiridion Hist. Nat. 1788, p. 37. 



Type, C. alba. 

 Species : — 



(«) Chionis alba (Gm.), Syst. Nat. i. 1788, p. 705: 

 jN'cw Year Island (coast of Staten Island). 



B. Chionarchijs Kidder & Cones, Bull. U.S. Nat. Mus. 



No. 3, 1876, p. 116. Type, C. minor. 

 Species : — 



(a) Chionauchus minor (Hartlaub), Rev. Zool. for 

 1841, 1842, p. 5: type-locality unknown. 

 Type in the Leyden Museum. 



It appears doul;tful whether, as is generally stated, the 

 Kerguelen Island Sheath-bill is identical with the bird named 

 by Hartlaub C. minor. Hartlaub, in his original description, 

 gives its location as " country unknown," and describes it 

 as distinctly smaller than C. alba. As a matter of fact, skins 

 of Sheath-bills from Kerguelen Island give measurements 

 which are quite as large as those of C. alba. 



The following comparative measurements, taken from the 

 skeletons of the two forms, may also be quoted : — 



(1) Sternum, length (over all) — Chionarchus " minor " . . 67 mm, 



,, ,, „ Chiimis alba 64 mm. 



(2) Humeru? — Cltionarchits '■'minor" 74 mm. 



,. Chionis alba 71 Jiuu. 



