VARIETY AND UNITY IX LIFE 



1") 



record of each year we find aljout twelve tliousand species, about 

 three times as many animals as in the whole " Systoina Natura*." 

 Yet the field shows no signs of exliau.stion. As the vohiiiics of 

 the "Zoological Record'' stand on tlie shelves, it is easy to see 

 that the later volumes are the tliickest; and tliose of the new 

 century, with a general revival of interest in systematic zoology 



Fig. 4. — California quail, Lopiionyx californicus. (Two-tliirds natur.-il ,si/,i-.> 



and the stud}^ of geographical distrihulion. -avo \]\c tlii<'k('si of 

 all. The depths of the S27,, the jungles of the t ropier, the crev- 

 ices of the coral reefs, the tundras of the north, the limhs of 



