444 Recent Literature. [q^J^ 



Degen on the "Perennial Moult" in the Australian Piping Crow. — 

 As shown by the title/ Mr. Degen's memoir is not merely an account of 

 the moult in one of the species of Australian Piping Crows, but an 

 attempt to throw light upon "the archgeornithic type from which the 

 wing of the modern bird has been evolved. The main object of the 

 paper is stated to be " to give additional evidence in support of the theory 

 of the derivation of the feathering of the bird's wing." If was therefore 

 found "necessary to ascertain the mode by which the perennial moult 

 of the individuals of a species of bird is made up from the earliest to the 

 last stages of renewal ; and, further, to what extent each feather partici- 

 pates in this annual process during tlie period of complete featlier- 

 change." The species chosen for this investigation is the GymnorJiina 

 tibiceu, in which the moulting of the flight-feathers is traced from the 

 beginning to the completion of the moult. The various stages, from the 

 dropping of the first remex to the completed growth of the one last 

 moulted, are described in detail and very clearly illustrated by numerous 

 diagrams. Not only is the moult in this species traced in the most 

 minute detail, but the history and previous literature of the general 

 subject of ecdysis is considered, mostly ^rt. •;.<//«, and tlie recent papers by 

 Mr. Witmer- Stone and Dr. J. Dwight are frequently cited, as well as 

 those of earlier writers. Beyond the minutely detailed record of the con- 

 ditions of feather-change in the Piping Crow, there is little that is new to 

 the general subject, but a confirmation of the conclusion reached by others 

 as to the order of shedding and replacement of the flight-feathers. The 

 two distinctly different principles of shedding and renewal are, first, " the 

 regular sequence of their renewal on the hand-portion from within out- 

 wards, though accelerated in certain places or retarded in others, in 

 order to maintain the requisite balance for flight, by a system of approxi- 

 mate symmetry for the whole wing during this critical cliange. This is 

 the principle which forms the rule for probably the entire order of the 

 Passeres," but not for some of the Picariie and many of the lower forms 

 of birds. In the case of the cubital quills the moult begins with the 

 first outer remex and proceeds inward to the fourth, but in the next 

 series of three the order of moult is reversed, beginning with the seventh 

 remex, then the sixth, and then the fifth. 



"The renewal of the wing-coverts presents some notable deviations from 

 that of the flight-feathers." While the latter assume their permanent 

 order of renewal in the first moult, the wing-coverts pass through transi- 

 tional stages before attaining tlieir permanent order of renewal. A 



' Ecdysis, as Morphological Evidence of the Original Tetradactyle Feather- 

 ing of the Bird's Fore-limb, based on the Perennial Moult in Gymtiorhina 

 tibiceii. By PMward Degen, F. Z. S. Trans. Zool. Soc. London, Vol. XVI, 

 Part viii, pp. 347-412, pll. xxxvi-xxxviii. May, 1903. 



^ Erroneously spelled " Wittmer" throughout the memoir. 



