SAND MARTIN. 403 



been made typical of a sub-genus ; and in looking 

 at the form of the typical Swallow there is a con- 

 siderable difference, but whether this should be 

 considered sufficient ground for separation, or 

 should be looked on only as modification of struc- 

 ture, seems not yet quite determined among 

 ornithologists ; and we now wish to direct atten- 

 tion to the little group to which it will belong, 

 and to the value of its characters when compared 

 with the species which begin to recede from 

 it. The Sand Martin is one of our earliest birds 

 of passage, reaching us often in March, and is 

 sometimes to be seen even amidst hail and snow. 

 On its first arrival, small groups visit their annual 

 breeding stations, and may be observed flitting 

 along some river-course or quarry-pool, or by the 

 margin of some lake, lazily and without their 

 usual activity, being without doubt wearied with 

 their migration, and yet able to procure but a 

 scanty subsistence. As the spring advances, the 

 various colonies arrive and take up their stations 

 for rearing their broods. These are chosen in 

 some sandy or easily pierced bank of a river 

 or sea shore, some quarry or sand pit, and the 

 sides are seen bored with numerous holes from 

 two to three inches in diameter ; they enter the 

 bank for a considerable length, and are formed by 

 the birds themselves scraping with the feet, as- 

 sisted by the bill, and at the extremity a loose 

 nest of dried grass lined with feathers is formed. 

 When the young are hatched and reared, they 

 assemble with the parents in considerable num- 



