" AQtriNTOCUBITALISM " IN THE BIRB's WING. 249 



C. torquata, G. rudis, G. alcyon, and G. maxima are diastataxic ; 

 the remaining species of the genus are eutaxic. In the genus 

 Salcyon, S. vagans, H. chloris, and H. sancta are diastataxic. 



D. gigas appears to be the only diastataxic member of the genus 

 Dacelo. 



The Macrochires comprise the Swifts (Cypseli) and the 

 Humming-birds (Trochili). 



The Trochili are all eutaxic. 



The Cypseli are mostly eutaxic, but contain at least two 

 genera possessing both foi^ms : — 



Dendroclielidon mystacea is diastataxic. 

 Acanthyllis collaris „ 



No satisfactory explanation of these exceptions has yet been 

 offered, though some sort of an attempt was made by the late 

 Henry Seebohm (6). He suggested that some diastataxic species 

 may have become eutaxic by elimination of the coverts belonging 

 to the missing fifth remex, thus removing all traces of their 

 former condition, i^'rom the facts already educed in the pre- 

 ceding pages of the present paper, this particular interpretation 

 must now be regarded as probably discounted. Before anything 

 like a final explanation can be hoped for, we must wait till more 

 material is at hand. A large series of embryo and adult species 

 of those genera containing both forms of wings will probably 

 settle the question. For the present, perhaps, the few suggestions 

 advanced on p. 252 may be acceptable. 



Facts correlated with Diastataocy. 



According to Seebohm (6) : — 



1. No eutaxic bird has a webbed foot. 



2. Birds which have abnormal plantar tendons contain both 



eu- and diasta-taxic species *. 



3. There are very few diastataxic birds without an ambiens • 



but there are no eutaxic families that contain birds both 

 with and without it f. 



* Concerning 2 it may be remarked that this is equally true of birds having 

 normal plantar tendons — Seebohm's term for plantar tendons in which the 

 flexor perforans supplies each of the front toes. 



t This depends upon the individual tasonomer — as to whether he eliminate 

 the discordant elements. 



