250 ME. W. p. PrCKAFT ON SO-CALLED 



' 4. Pelargomorphse have normal plantars and are diastataxic. 



5. ^gitlioraorphse have normal plantars but are eutaxic. 



6. Coraciomorphse contain both diasta- and eutaxic forms. 



Of four diastataxic families two contain both eu- aud 

 diasta-taxic species. 



According to Degen : — 



" Aquiutocubitalism and Quintocubitalism seem to reflect 

 on the presence or the absence of the 11th metacarpo- 

 digital flight- feather." (All 11-priniaried birds are 

 diastataxic according to this author.) 



According to Groodchild : — 



The diastataxic wing is characterized by a peculiar inter- 

 ruption or faulting of the coverts of the dorsal 

 surface. 



Degen's contention is disproved by the fact that, as shown by 

 Gradow (2), the following, though diastataxic, have only 10 

 primaries : — Scopics, Eurypyga, Hallus, Ocydromus, Ilimantoriiis, 

 Psittaci, some Cypselidse, Caprimulgus, and Megapodius. 



Again, many Cypselidse, Eurylcemus javanicus, Acanthyllis 

 caudacuta, and Geryla americana have 11 primaries, but are 

 eutaxic. 



Groodchild's ohservation refers only to the external phenomena 

 of the relative length of the feathers composing the different 

 rows in this region of the wing. This " faulting " is not always 

 visible in diastataxic wings, as is well seen in many Parrots for 

 instance. 



Some Degenerate Wings, 



In the present connection it will be sufficient to survey this 

 subject briefly. In the most perfect form of wing it will be 

 noticed (PI. 14. fig. 5) that the manus is longer than the forearm^ 

 and that the angle Avhich the primaries form with the skeleton 

 changes more and more from within outwards ; the innermost 

 remex lying at a right angle to, and the outermost parallel with, 

 the long axis of the wing. Thus it comes about that the wing-area 

 of the hand is as great as, or greater than, that of the forearm. 

 Correlated with the form of the wing is the nature of the flight. 

 Thus, in the Swifts and Albatrosses the wing is ribbon-shaped.-^ 

 very narrow from the pre- to the post-axial border, and much 

 produced outwards. In birds like the Heron, the wing is very 



