XXIV 



The rudimentary quill on the carpus is marked 1'. It is 

 found generally in a vestigial state of growth in the majority 

 of birds, but, as -sre have seen, in some instances, such as in 

 the Gulls, there is an actually developed quill-feather. This 

 fact is indicated in the diagram by dotted lines, the quill 

 being represented as of full value with the other remiges,, 

 as it undoubtedly was at one time. 



The "carpal" covert in its true intermediary position is 

 best seen in the Ducks. It has been cut short in the Plate 

 (fig. ]) and coloured red. 



The metacarpo-digitals, numbered 1-11, represent the 

 normal number in most birds, including the " remicle,^' 

 which is really the 11th metacari)0-digital remex (mostly 

 rudimentary)*. 



The quills of the ala spuria are marked A.s. in the diagram^ 

 to the number of 4 on the 1st phalanx of the 1st digit. 



Fi^. 2 in the Plate is intended to show merely the fore 

 limb of the bird, with the component osseous parts slightly 

 interspaced, for greater distinctness, at their respective 

 joints. 



The 2nd and ord metacarpal bones are intersected by dotted 

 lines. In fully adult birds these bones are ankylosed at their 

 epiphyses, but they are completely separate in the embryo. 



In the Penguin, however,, as may be seen in the specimen 

 exhibited in the Index Series of the British Museum (Natural 

 History), we find a very good example of an intermediate 

 stage, where the ankylosis still indicates the original sepa- 

 ration of the bones. It indicates, in fact, the original 

 polydactyle plan in the mauus of this class oi: Auamniotic 

 \ ertebrates. 



The skcletiferous parts, as seen in fig. 3 of the Plate, 

 are the same as those in fig. 2, but are divided up to the 

 clbow-joiut in a longitudinal section, so as to allow rne space 



* There is great coufu.siou as to the value uf the so-called " remicle." 

 j^oinetimes this is treated as a veme.t, suujetimes as a covert. There 

 ought to he no ditRculty in this matter, for when it is au aborted remex 

 it shi/w? th--' tact liy it- imbrication, and wIumi it i~ a covert it lies in a 

 siiptiior position i.ud i^- dist-illv iuilrica:>.d by the adjoiuii:;r covcrt. 



