8430 Notices of New Books. 



Flora, and their bill is well suited to the capture of the minute insects 

 found in those elevated regions. In some instances the bill is perfectly 

 wedge-shaped, as in Heliothrix, while in others it suddenly turns 

 upwards, as in Avocettula. These forms are also adapted for some 

 special purpose, of which, however, at present we are ignorant. Besides 

 these there are others whose bills approach somewhat to the form of 

 the flycatchers, as the Aithurus. This bird we know frequently seizes 

 insects on the wing, and so doubtless do many of the others. It will 

 have been seen that all these forms of bill are well suited for the cap- 

 ture of insects, and, as might be supposed, insects constitute the prin- 

 cipal food of the humming bird, but that liquid honey, the pollen and 

 other saccharine parts of flowers are also partaken of is evident from 

 the double tubular tongue with which all the species are provided. 

 Besides this they readily and greedily accept this kind of food when 

 offered to them in a state of captivity, or when the corollas of a bouquet 

 of flowers placed in a window are filled with sugar to entice them to 

 approach ; and from my own experience I know that they have been 

 kept in captivity for several months upon this kind of food." 



Here then we have all that Mr. Gould has to say on the important 

 subject of food, and it must be admitted by all true naturalists that 

 the very diversity of food, and in the manner of feeding, are important 

 characteristics of the tribe. Among other groups of birds we find 

 constancy of food an excellent guide in classification ; thus the swallow 

 tribe may be associated and distinguished by their propensity to cap- 

 ture exosteate animals on the wing; the hawk tribe have a like pen- 

 chant for living endosteates ; the vulture tribe for dead and putrefying 

 endosteate carcasses; the herons for fish, and so on; but when we 

 examine such a heterogeneous tribe as that called the passerine birds 

 we find it contains consumers of every different kind of food ; thus we 

 have bird-eaters, insect-eaters, grain-eaters, fruit-eaters, &c, and indeed 

 many groups which seem absolutely omnivorous. Mr. Gould finds 

 amongst the humming birds, muscivorous, arachnivorous, mellivorous 

 and pollenivorous species, thus making out a prima facie case for 

 considering the group of diversified food and economy, and leading to 

 a conclusion, also prima facie but inevitable, that a group thus diver- 

 sified is of greater extent than hitherto ascertained, and of proportionate 

 importance in a natural system. I will revert to this subject almost 

 immediately, and will suggest another possible cause for the diversity 

 in question ; but I must first pause for a moment to consider Mr. 

 Gould's mention of pollen and other saccharine parts of flowers. The 

 slight obscurity of these words induces me to pen the following queries. 



