294 



REPORT OF NATIONAL MUSEUM, 1890. 



serve for the passage of nectar from flowers seeras a little doubtful, the peculiar modi- 

 fication of the tongue probably being for the capture of minute insects. The ante- 

 rior half of this membraneous flange is more or less fringed, as noted by Gosse and 



FIG. 3. The accompany ins figure of the head of a Humming Bird (Eulampis holosericeus), seen from 

 above, shows the termination of the hyoid, or tongue, bones h. The shaded bands indicate the 

 muscles whica retract the tongue. (The figure is twice the natural size.) 



others, but how much of this fimbriation is normal and how much is due to the 

 whipping out of the membrane by use is not quite evident. That some of the iim- 

 briatiou is due to wear is certain from its appearance under the microscope. 



FIG. 4. Tho accompanying figures, showing del ails in the structure of the tongue of a Humming 

 Bird (Eulampis holosericeus}, may be described as follows : 



No. 1 shows the tongue, twice the natural size, with the free portions separated and the membrane 

 spread out. 



No. 2 shows the anterior portion of the tongue, greatly enlarged, with the membraneous fringe 

 curled up, as in life. 



Nos. 3, 4, and 5 ar-e sections through the tongue at 3', 4', and 5', greatly enlarged. 



No. 6 represents the termination of one of the free portions of the tongue very much enlarged. 



VARIATIONS. 



The raDge of variation in the details of form or external structure, 

 size, and coloration in the Humming Birds is very great perhaps more 

 so than in any other group of coordinate rank among birds, this varia- 

 tion affecting chiefly the bill, as to its proportionate length and whether 

 straight or curved, and if curved to what degree and in what direction ; 

 the tail (which, however, always consists of ten rectrices?)*, in the rela- 

 tive length of different feathers, one or more pairs of which are some- 

 times singularly or even extraordinarily developed or aborted ; and the 

 wing, as to the shape of the outer primary and the thickness of its 

 shaft. These variations are so complex, however, that it will be best 

 to treat of them under distinct headings. Indeed "it is the great 

 diversity of form in this family of birds, " says Mr. Gould, "which ren- 

 ders the study of them so very interesting. If these little objects were 



* See remarks as to this on page 300. 



