284 BULLETIN 146, UNITED STATES NATIONAL MUSEUM 



the greenish ones from " water green " to " yellowish glaucous." One 

 plain-looking egg is " dark olive buff " with faint markings of a 

 slightly darker shade. Another is " water green " with numerous, 

 small, almost black spots, and underlying small spots of " light mouse 

 gray." The measurements of 100 European eggs furnished by the 

 Kev. F. C. E. Jourdain, average 40.5 by 29.2 millimeters; the eggs 

 showing the four extremes measure 44.5 by 30.4, 43.2 by 31.3, 36 by 

 28.2 and 40.5 by 26 millimeters. Mr. Brandt^s 44 eggs, from Alaska, 

 average slightly smaller, 39 by 28 millimeters; the extremes of his 

 and all other American and Greenland eggs that I have measure- 

 ments of fall within the limits given above for European eggs. Egg 

 measurements would seem to indicate that Alaska birds should be 

 referred to monnella^ the smaller race. 



Young. — The period of incubation does not seem to be Imown, but 

 it is a well-established fact that both sexes share in this duty, as well 

 as in the care of the young. Mr. Paget- Wilkes (1922) says: 



Both sexes incubate, but when the eggs are fresh or partly incubatetl the hen 

 seems to brood and the cock stands on guard. When the eggs were within a day 

 or two of hatching or were just chipping we invariably found the cock incubat- 

 ing, and when the young were out we always found the cock looking after the 

 family and the hen, with her duller plumage and weaker notes, on guard. 

 These characteristics observed in the cases of 19 pairs should form a useful 

 basis for further research. 



On flushing the cock bird from four young in down on the Mouettes Islands 

 I was shown an example of his tenacity and intelligence. I had taken the young 

 birds away in my pocket and had run back to the boat across a neck of land 

 some 300 yards broad. The cock chased me a little way and then disappeared. 

 On reaching the sea, however, on the other side of the small peninsula, I imme- 

 diately saw the cock fly around the point and make straight for me, and he 

 stood and chattered at me until we rowed away in the boat. The hen put in 

 no appearance at all. 



Again, on one of the islands we watched a pair whose behavior puzzled us, 

 but soon discovered that there were four young birds being looked after by the 

 cock. The moment he was flushed the young birds scattered in all directions, 

 and on our lying down again came back under the fatherly wing. Before I 

 discovered that the cock incubated in the last stages I patiently watched a hen 

 running about quite unconcernedly for almost an hour, and then suddenly 

 jumped to the conclusion that the cock was sitting. When I got up the hen 

 gave the alarm note and I flashed the cock from four chipping eggs. 



A. L. V. Manniche (1910) writes: 



The parents are very watchful against danger in the breeding time and when 

 the young ones are small. One of them will keep a lookout from the summit of 

 a large stone or a rock while the other is brooding or guiding the young ones. 

 The bird on guard will discover an approaching enemy at an incredibly long 

 distance and rush toward him uttering furious cries. Especially the skua 

 (Lestris longicauda) is a detested enemy of the turnstone. Every day I could 

 observe the hunting skuas pursued by turnstones. When one pursuer returned 

 to its district another would appear and thus every skua was almost always 

 accompanied by at least one turnstone. Also toward the polar fox the turn- 



