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- 
