MB. E. DEGEN ON ECDTSIS. 401 



towards that point which forms the focus in the whole problem, viz. the diastema, for 

 the position of the 5th cubital remex. The space between the first primary remex on 

 the metacarpus and the sixth secondary one is occupied by cubital remiges I.-V. 

 (exclusive of a carpal vestigial one), with their respective main coverts, which form the 

 most distal group on the forearm, and here spoken of as Group II., on account ot 

 the moulting of these feathers second in order, and therefore in keeping with this 

 particular feature. 



All the members of this group moult in inverse order, viz. from the wrist-joint 

 inwards. To these, in my former diagram (pi. i. fig. 3, I. c.) of the reconstructed wing, 

 was allotted a metacarpal position ; and, in allusion to their possibly former digital 

 derivation, they were referred to as " proto-metacarpo-digitals." 



The significance of a similar fact of the '■'■ pennce polUcis" moulting in an inverse 

 direction, too, assumes now additional importance through this peculiarity. As 

 mentioned before (p. 371; see " x\la spuria"), that it probably would matter little 

 whether these feathers were regarded from a purely remigial or a tectricial point of 

 view ; this again finds corroboration in this place, since main coverts follow the same 

 routine order of moult as do remiges. But what really transpires is (especially when 

 taken in conjunction with the sectional moulting of the flight-feathers on the manus, 

 as in the Kingfishers and others, and further shown for the dorsal median coverts in 

 this species) that we have clear testimony in this of the presence of a distinct digital, 

 and an equally distinct metacarpal, element. To the remiges of the former derivation 

 therefore alone belongs the term proto-, whilst to the latter belongs that of hypo- 

 metacarpo-digitals. 



If then, as the principle of analogy would justify us in adopting, the same rule by 

 which the remiges of the former Group II. (and now become our Hypo-inetacarpo- 

 digitals, or further abbreviated " Metacarpals ") were applied to our permanent meta- 

 carpo-digitals I.-X. (XI.) (or frequently more as in the Ostrich and probably in the 

 archseornithic wing), the only possible inference would be that these latter are those 

 of purely digital origin. 



As such then, and the fact that both sections of which the series is made up, viz. 

 from I. -VI., and the other from VII.-X. (XL) and moulting both in an outward 

 direction, it is these which now become our true " Proto-metacarpo-digitals " of the 

 hypothetical wing. 



In the " modern wing '' those of the outer section alone, namely, primary remiges 

 (VII. ]) VI.-X. (or XL), deserve henceforth the appellation of " Permanent Digitals " 

 (see former diagram). On the other hand, the primaries of the inner section, 

 viz. I.-VI. (having, in association with synostosis of the metacarpal bones belonging 

 to digits II. and III., been borrowed from their previous phalangeal position on 

 digit III. by the now combined metacarpal bones Avith which they have become 



