VOL. I.] Life History of the House Finch. 175 
grow more sharply defined each succeeding day. The shape of the 
bill undergoes a decided change. At first it is soft, being but slightly 
harder than skin, and its contour is perfectly regular. Each day 
produces a slight change in its shape until the end of the first week, 
by which time it has assumed a form very similar to that of the 
adult bird, and from this time on it, hardens very rapidly. 
In the young bird the skin is extremely transparent, so much so 
that the food can be distinctly seen in the crop. The crop is but 
little distended on the first two days, but by the third day hangs 
about the neck like a loose sack. It contains fine particles of green 
food, much of it appearing to be the fine undeveloped seeds of some 
plant. The growth of the young bird is rapid and constant. In 
ten days the chord of the culmen had grown from four to eight 
millimeters, the gape had increased from five and a half to eleven 
millimeters, and the tarsus from five to fourteen millimeters. In 
fact, the bird just about doubled its size in these first ten days. The | 
feet develop more rapidly than any other part, and the head is the 
slowest in growing. 
From the third day on, the growth of the feathers is continuous. 
At that time the wing quills first make their appearance, and 
by the sixth nearly all the feathers have sprouted. Figure 5 repre- 
sents the bird on the eighth day. By this time the feathers on the 
breast have begun to emerge from their sheaths, giving the fledg- 
ling quitea novel appearance. It now looks much more mature, 
as the legs and wings are better proportioned to the size of the body 
than during the earlier stages, and the belly is slowly growing less 
prominent. Figure 6 shows a rear view of the same bird on the 
following day. The remarkable growth of the wing quills is one ot 
the most interesting features. The distribution of the dorsal feather 
tracts is also shown in this figure. Figure 7 is a front view of the 
bird on the eleventh day. The wing quills are still growing rapid- 
ly, and the ear coverts, which are the last feathers to sprout, have 
made their appearance. The tail feathers, which were first notice- 
able on the ninth day, are growing quite fast, although their devel- 
opment is slower than the wing quills. It will be noticed that the — 
piloplumules are still present. Though less erect than at first, they 
- are not shed until all the feathers are grown, and I have noticed 
them in the head of a fully developed bird. 
_ The male does not appear to aid in caring for the young. The 
