50 Zoological Society : — 



Montagu, in his Ornithologic.il Dictionary, says he " discovered 

 the nest of this bird in consequence of the old bird flying, with a fish 

 in its bill, to the young. These were nearly fledged, but incapable of 

 flight ; and the moment the nest was disturbed, they fluttered out 

 and dropped into the water, and, to our astonishment, instantly 

 vanished, but in a little time made their appearance at some distance 

 down the stream, and it was with difficulty two out of five were taken, 

 as they dived on being approached. The motion under water," he 

 says, " is effected by short jerks from the shoulder-joint, not, as in 

 all other diving-birds, with extended wings." 



Yarrell dissected this bird, and found nothing in its structure to 

 account for its diving and remaining on the ground without any 

 muscular effort. 



Mr. Macgillivray (Naturalist, vol. i. p. 105) says, " I have seen the 

 Dipper moving under water in situations where I could observe it 

 with certainty, and I readily perceived that its actions were similar 

 to those of the Divers, Mergansers, and Cormorants, which I have 

 often watched from an eminence as they pursued the shoals of sand- 

 eels along the sandy shores of the Hebrides. It in fact flew, not 

 merely using the wing from the carpal joint, but extending it con- 

 siderably, and employing its whole extent as if moving in the air. 

 The general direction of the body is obliquely downwards ; and great 

 force is evidently used to counteract the effects of gravity, the bird 

 finding it difficult to keep at the bottom." 



Other observers have given similar testimony, some asserting that 

 bubbles of air appeared on the surface after the bird was submerged : 

 but these must have arisen from the disturbance of the earth at the 

 bottom of the river ; for no diving-bird, I believe, emits air from its 

 lungs when under water. The air is got rid of before the act of 

 diving takes place. But let me now speak of some parts of the 

 anatomy of this bird, before I attempt to answer the first question. 

 The average weight of this bird is said to be 2\ oz. ; but in four that 



I have weighed the average weight has been about 2\ oz., the males 

 being a little heavier than the females ; the length 7\ inches, and 



II inches from the tip of each wing. The brain weighed 10 grains, 

 the eyes 12 grains, the skin and feathers 132 grains, the pectoral 

 muscles 135 grains. The gizzard moderately thick, and lined with 

 a tough cuticle. The length of the whole alimentary tube was 

 1 G inches ; the oesophagus, as in the other Merulidce, not dilated 

 into a crop. The trachea of nearly uniform calibre, and consisting 

 of 36 rings ; the vocal muscles largely developed, as in the other 

 members of this family. The tail-glands comparatively of large size. 



I have depicted all the above parts in the drawing before the 

 Society ; but the parts of the anatomy of this bird to which I am 

 anxious to direct attention are the shortness of the wing and the great 

 development of the wing-muscles — features which I believe will iu 

 a great measure account for the diving-powers of this bird and its 

 progress under water. As might be expected, too, from the frequent 

 motion of the tail, the caudal muscles are much developed. On 

 comparing the visceral anatomy of this bird with that of the other 



