" QUINTOCUBITALISM " IN THE WING OP BIRDS. 211 



-there is a variable remex, whicli when normally developed, as in 

 JSfotJiura, is in obvious series with the cubital remiges, and which 

 is frequently smaller in size but connected to the cubital series by 

 a special plica of membrane as in most pigeons, but which may be 

 :absent ; although in the case of the Columbse, to which this memoir 

 has special reference, I have not noticed a case of absence. 

 I believe the simplest way to state the facts is to adhere strictly 

 to the division of the remiges or wing-quills into primaries and 

 secondaries, to consider the carpal remex as the first secondary, 

 and then to say that, after the fifth secondary, there may be a gap 

 more or less equivalent to the space which would be occupied by 

 a sixth secondary in even series, after which the secondaries 

 continue in normal series ; or that the secondaries may all lie in 

 normal series without the occurrence of a gap. Eor the first 

 condition, that hitherto known as " aquintocubital," I propose 

 the term " diastataxic " ; for the second condition, that known 

 ,as " quintocubital," I propose the term " eutaxic.^'' These new 

 terms are simply descriptive ; they convey no implication as to the 

 •way in which the two conditions arose, and they appear to me to 

 be equally applicable, whether we accept the current view that 

 the diastataxic coudition has come about by the disappearance 

 of a fifth secondary from an eutaxic series, or if, as I believe, 

 there is no lost feather. If there be no missing feather, it is 

 obvious that the diastataxic condition might have arisen from 

 the eutaxic condition by elongation of the wing in the region 

 of the gap without the addition of a quill to the series ; or that 

 the eutaxic condition might have come from a diastataxic con- 

 dition by the closing-up of the quills without consequent oblite- 

 ration of the gap. I hope in this memoir to show reasons for the 

 latter view — for, in fact, the view that the diastataxic condition 

 is architaxic. 



Tor some time I have been engaged in a special study of the 

 Columbse. These, like most of the larger groups of birds, have 

 been described as diastataxic, and, without question, the wing 

 in the majority of them presents a well-marked gap. This is 

 well seen in the wing of a common pigeon, where the gap is as 

 large as in a duck or in an eagle, and is occupied by an apparently 

 normal covert. In Turtur chinensis (PI. 13. fig. 7) there are ten 

 primaries with their major coverts placed (as I find invariably 

 .among the Columbidse) distally to the corresponding quills ; then 

 ■comes a moderately-sized carpal remex bound down by a special 



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