230 HIRUNDINIDE. 



passes, while others are more irregular in form ; but tliis 

 seems to depend more on tlie sand crumbling away than upon 

 any deficiency in the original workmanship. The bird, in 

 fact, always uses its own body to determine the proportions 

 of the gallery, — the part from the thigh to the head forming 

 the radius of the circle. It does not trace this out as we 

 should do, by fixing a point for the centre around which to 

 draw the circumference ; on the contrary, it perches on the 

 circumference with its claws, and works Avith its bill from the 

 centre outwards : and hence it is that in the numerous exca- 

 vations recently commenced, which we have examined, we 

 have uniformly found the termination funnel-shaped, the 

 centre being always much more scooped out than the circum- 

 ference. The bird consequently assumes all positions while 

 at work in the interior, hanging from the roof of the gallery 

 with its back downwards as often as standing on the floor. 

 We have more than once, indeed, seen a Bank Martin 

 wheeling slowly round in this manner on the face of a sand- 

 bank, when it was just breaking ground to begin its gallery. 



All the galleries are found to be more or less tortuous 

 to their termination, Avhich is at the depth of from two 

 to three feet, where a bed of loose hay, and a few of the 

 smaller breast-feathers of geese, ducks, or fowls, is spread 

 Avith little art for the reception of the eggs. It may not be 

 unimportant to remark, also, that it always scrapes out with 

 its feet the sand detached by the bill ; but so carefvdly is 

 this performed that it never scratches up the unmined sand, 

 or disturbs the plane of the floor, which rather slopes 

 upwards, and of course the lodgment of rain is thereby pre- 

 vented." 



The eggs are from four to six in number ; white, like 

 those of the House Martin, but smaller, measuring only 

 eight lines in length, by six lines in breadth. The Sand 

 Martins are sociable birds, building in company close to 



