•254 • TVIK. W. p. PrCRAFT ON SO-CAtiLED 



Diastataxy as a Factor in Classification, 

 If it be true that diastataxy is au indication of a more or less 

 remote degree of consaoguinity, as has ju^t been hinted, or, in 

 other words, if diastataxic forms are more nearly related one to 

 the other than those which are not, we may find this character, 

 used with discretion, no small help in systematic work. I say 

 used with discretion advisedly ; for it is incontrovertible that the 

 nature of the evidence from other sources makes it absolutely 

 impossible to use this character as a primary factor, wherewith 

 to divide the Class Aves into two great groups, eu- and diasta- 

 taxic. But the presence of diastataxy in a little coterie of forms, 

 admittedly related, but hitherto indiscriminately mixed with 

 eutaxic, will be a sufficient reason to justify our separating them 

 out to form a group by themselevs, on the assumption that the 

 character was inherited from a common source, and that they are 

 therefore more closely related one to the other than to the neigh- 

 bouring eutaxic forms. The presence of discordant elements in 

 the shape of eutaxic forms amongst our now diastataxic groups — 

 such as the Kingfishers, Swifts, and Pigeons — must be attributed 

 to reversion or secondary readjustment of the feathers resulting 

 once more in eutaxy. This is not as convincing as it should be ; 

 but it demands less of us than the alternative hypothesis, that 

 diastataxy has been independently acquired wherever it occurs. 



The result of the slight shifting here suggested is in no sense 

 revolutionary in its tendencies. Amongst the Picarian forms it 

 would bring together the Psittaci, the Striges, and the Capri- 

 mulgine forms associated therewith, the Swifts and Humming- 

 birds and the Kingfishers — all diastataxic, drawn from the ranks 

 of eutaxic forms to constitute a little coterie by themselves, 

 l^be Megapodes would be cut off from the remainder of the 

 (xalline forms, which are eutaxic, just as ELeliornis, PsopJiia, 

 Qariama, BhinocJietus, and Euryjjyga remain as every modern 

 systematist has left them — as isolated and aberrant groups in 

 the neighbourhood of the Grues. Gariama remaining as a sort 

 of sign-post pointing the way, as Beddard has recently shown, 

 from the Grues to the Aecipitres. 



'This scheme is doubtless open to criticism; but this may be 

 said of every other. 



