UNCLE IN ENGLAND. 143 



sufficient proofs of their belonging to indigenous, 

 or, at least, to modern races of plants ; while 

 those which occur in what is termed black coal 

 are all unknown or exotic : there can be no 

 doubt, therefore, that those two coal formations 

 belong to two very different ages of the globe." 



26th. I still find a great deal of amusement 

 in watching my little family of swallows. They 

 are unwearied in collecting food for their young ; 

 skimming through the air from morning till 

 night, and darting on their prey with the most 

 sudden turns. They catch gnats and flies, and 

 consume an astonishing number of mischievous 

 grubs ; and I am told they often accompany 

 people on horseback, through the fields, in order 

 to pick up the flies which are roused from the 

 turf by the horses' feet. 



They never touch seeds ; insects are their only 

 object, and according to the weather, or the de 

 gree of warmth, they sometimes skim along the 

 surface of the ground, and sometimes fly at a 

 great height. When there is a scarcity of insects 

 they have been known to snatch the flies impri- 

 soned in a. spider's web, and sometimes even the 

 spider itself. 



Another species arrived soon after the chimney 

 swallow, which I. believe I have already de- 

 scribed to you. It is called the house martin, 

 or window swallow ; but there is no end to the 



