LIFE HISTORIES OF NOETH AMBKICAN DIVING BIRDS. 193 



among the eggs looking them over and even poking them about with 

 its bill until the right one was found. Sometimes a mistake is made 

 and the rightful owner finds a stranger sitting on its egg, which 

 leads to a little squabble. That both sexes incubate I have proven 

 by finding both males and females with bare abdominal spaces. The 

 incubating bird sits in a horizontal position and does not " straddle " 

 its single egg in an upright position, as has been stated; while one 

 of a pair is incubating the other frequently stands beside it. 



Eggs. — ^The eggs of this species show such striking and endless 

 variations in color patterns that any attempt to describe them can 

 not but fail to convey an adequate idea of what a large series of 

 these beautiful eggs will show. The prevailing ground color is 

 bluish green or greenish blue, varying from pale bluish white to 

 deep " Nile blue " or from pale greenish white to " glaucous green," 

 pale " beryl green " or " malachite green " ; pale shades of " apple 

 green " or " oil green " are rarely found ; sometimes the ground color 

 is pure white, varying to " cream buff " or " olive buff." Abso- 

 lutely spotless eggs of the lighter shades are occasionally found. 

 Many eggs are more or less covered with small spots of various 

 shades of dark brown and a few show underlying blotches of lilac 

 or " ecru drab " ; many are beautifully or fantastically scrawled with 

 irregular markings of "ecru drab," "wood brown," "raw umber," 

 "sepia," or "clove brown." But the prevailing types are more or 

 less heavily blotched, spotted or scrawled with course markings of 

 the last two shades. These blotches are often confluent in rings 

 about the larger end of the egg. Some particularly handsome speci- 

 mens are heavily clouded with lUac and light brown, overlaid with 

 blotches of darker browns. They vary greatly in shape but are 

 generally pyriform and elongated. The measurements of 41 eggs, 

 in various collections average 80 by 50 millimeters; the eggs show- 

 ing the four extremes measure 87.5 by 53.5 and 67.5 by 43 milli- 

 meters. 



Young. — ^Aiter a period of incubation lasting about 28 days the 

 young murre is hatched in a weak and helpless condition. It is 

 brooded and fed by its parents until it gains sufficient strength to 

 move about, but it grows rapidly and soon becomes very lively. 

 While in the helpless downy stage it makes a very shrilly but faint 

 peeping noise; but when about half grown and clothed in its soft, 

 Juvenal plumage it can stand erect and walk or run about on the 

 ledges, uttering its loud, shrill, emphatic cries, which sound to me 

 like the syllables "beat it, beat it, beat it." The cliffs fairly re- 

 soimd with the cries of the young at this season, the last week otf 

 ' July or first week of August on Bird Kock; it is the most critical 

 ' period in their lives, for then it is that their parents are persuading 

 them or forcing them to leave the cliffs, long before they can fly, and 



