382 MR. E. DEGEN ON ECDTSIS. 



duhital Portion. — Tliis row of covert-feathers being suppressed in all the Passerine 

 birds, no positive information is available through this species for their beliaviour 

 under conditions of moult. 



A provisional examination of a diastataxic species {Plafjjcercus eximiiis) shows 

 that there is no material deviation from the moult of their dorsal congeners as regards 

 synchronism Avith their remiges, excepting perhaps that they exhibit a tendency to moult 

 somewhat earlier than the latter and also adhere to the juvenile mode of simultaneous 

 replacement through more than one perennial change. 



Tectrices secundse serii or Tectrices mediae. 

 1. Superiores. 



Metacarpo-digital Portion. — In striking contrast to the order of the moult which 

 is adopted by the first series of satellites in relation to the remiges, stands that of the 

 second series, or the medians. 



In the former, as we have seen, it consisted in a rhythmical accompaniment to their 

 remiges in the order of the growth of the latter. Not so for the dorsal median 

 coverts. Their renewal proceeds from two separate points on this portion of the wing. 



The first of these two points, the earlier one at which moult sets in, is identical 

 with remex I. and its upper major covert. Its moult, however, does not synchronize 

 with these, because the earliest signs of moult of median coverts do not appear until 

 after the renewal of from 4-5 remiges with their principal satellites has taken place. 



The second point at Avhich moult sets in on the manus coincides with remex VII., 

 and proceeds in the same outward direction as does that from the proximal centre. 



This different mode of I'enewal therefore bisects the hand-portion into two areas : 

 a first or proximal one comprising median coverts 1-6, and a second or distad section 

 made up by coverts 7-10. In birds at the beginning of the moult, and in which not 

 more than from 2-4 remiges are in process of renewal, as yet no medians make their 

 appearance. 



The earliest specimen on the list in which the first and innermost of median 

 coverts is being formed is No. 3 on its right-side wing, which has reached the stage 

 of e (see also Diagr. B, Plate XXXVL, right side), or the moult of remex V. 

 The next specimen is No. G, on the right side, too, of which median coverts 1 

 and 2 are in course of formation. Its stage of development for remiges is the 

 same as that of the previous specimen, viz. that of remex V., which denotes a 

 slightly more advanced condition here. This specimen, moreover, has reached a more 

 advanced condition on its left side, where median covert 3 is being renewed also. 

 The renewal of 3 median coverts, however, generally coincides with that of remex VI., 

 which is the more normal course which these coverts pursue. This is well defined on 

 the right side of No. 9. 



