Systematic Position of the Sheath-bills. 129 



break open and feed on, while they have actually been seen 

 to rob sitting birds. This is mentioned by Eagle Clarke, 

 Menegaux, and Eaton (Phil. Trans. Roy. Soc. vol. clxviii.). 

 Such habits are sufficiently surprising in a Wader, and are 

 more reminiscent of a Skua or a Gull. 



On a j>ap formed of the placentae of seals, the contents of 

 eggs, and small Crustacea (Isopods), on which the Sheath- 

 bill also feeds, one could well imagine that the young are 

 nourished by the parents for some time and while still in 

 the nest. Eaton records that the Sheath-biil also feeds, 

 between tide-marks, "on mussels, enteromorpha, and ulva." 



The birds nest in colonies on the edge of Penguin or 

 Shag rookeries, the nests being "placed in crevices of rocks 

 or underneath boulders on the moraine,^^ sometimes ten or 

 twenty feet only above sea-level, at other times a good deal 

 liigher up. One was found during the Scottish Expedition, 

 100 feet up on a moraine and "right in the midst of tlie 

 Penguins'' (Eagle Clarke). The nests were mainly composed 

 of the shells of Penguins' eggs, bones, feathers, and a number 

 of limpet-shells (Eagle Clarke). Eaton [I.e.) says: "The 

 nest is a simple construction without a lining, and consists 

 of a heap of dried seed-stalks of Pringlea antiscorhutica or 

 tufts of Festuca erecta. Occasionally old burrows of Prion 

 or Halobana are occupied.'' In the South Orkneys the 

 birds were migratory, and, in the main, only visited these 

 islands to breed. During winter only some twenty or 

 thirty remained and " eked out an existence on the refuse 

 odds and ends which were daily thrown out from the 

 ' Scotia ' " (Eagle Clarke) ; a proceeding, it may be added, 

 which does not suggest the habits of the normal Wader. 



III. Pterylography. 



A. Embryo of Chionarchus minor, nearly ripe, obtained 



from Kerguelen Island on the 'Challenger' Expedition 



and now in the collection of the British Museum. 



The type of down-feathers presented by this and all the 



embryos I have examined is prepennal only. These pre- 



pennal down-feathers are disposed in well - defined and 



SER. X. VOL. IV. K 



