LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 31 



is, as I have said, composed of a pile of moss, in shape a truncated cone, and 

 may be from 6 to 9 inches in height and from 18 inches to 2 feet in diameter. 

 There is no hollow on, the top of this more or less level pile, upon which the egg 

 is deposited or the young bird sits. I noticed many dead young birds, some quite 

 recently deceased, for they were still warm, while others had been dead for 

 some time. In nearly every case their crania had been indented. 



Doctor Malmgren, of the Swedish expedition to Spitzbergen in 

 1861, found a colony of ivory gulls breeding in entirely different situ- 

 ations. Baird, Brewer, and Kidgway (1884) quote from his notes, as 

 follows : 



On the 7th of July, 1861, 1 found on the north shore of Murchison Bay, latitude 

 80° N., a number of ivory gulls established on the side of a steep limestone 

 precipice some hundred feet high in company with the Rissa tridactyla and 

 Larus glaucus. The last named occupied the higher zones of the precipice. 

 The Larus eburneus, on the other hand, occupied the niches and clefts lower 

 down, at a height of from 50 to 100 feet. I could plainly see that the hen birds 

 were sitting on their nests, but these were inaccessible. Circumstances did not 

 permit before the 30th of July my making the attempt, with the help of a 

 long rope and some necessary assistance, to get at the eggs. With the assistance 

 jf three men I succeeded in reaching. two of the lowest in situation, and each 

 contained one egg. The nest was artless and without connection and con- 

 sisted of a shallow depression 8 or 9 inches broad in a loose clay or mold on 

 a sublayer of limestone. Inside the nest was carefully lined with dry plants, 

 moss, grasses, and the like, and a few feathers. The eggs were much in- 

 cubated and already contained down-clad young. Both of the hen birds were 

 shot upon their nests and are now in the National Museum. The male birds 

 were at first observable, but disappeared when we began the work of reaching 

 their nests. 



Eggs.— The ivory gull lays a set of one or two eggs. Two of 

 the eggs taken by Captain Johannesen are in our National Museum, 

 and Major Bendire (1888) has described them as follows: 



Their ground color is buffish olive ; in one egg, somewhat paler, perhaps more 

 of an olive-drab tint. The surface markings, more or less irregularly dis- 

 tributed over the entire egg,- vary from clove-brown to bistre. The underlying 

 or shell markings vary from slate to lilac-gray in tint and predominate in the 

 larger specimen. In the smaller and darker one, both styles of markings are 

 about equally distributed. The two kinds of spots vary considerably in size 

 and shape. 



Professor Collett (1888) describes nine of the eggs, as follows: 



The ground color of five specimens is almost entirely alike — viz, a light 

 grayish-brown tint, with faint admixture of yellowish green, such as often 

 appears on the eggs of L. carws; which, however, have often a deeper brown 

 or green hue. In structure and gloss all nine eggs greatly resemble those of 

 L. canus; but the granulations under the microscope are a little coarser, more 

 uneven, and in larger numbers; on the other hand, the granulations are per- 

 ceptibly finer than in. L. fuscus. The eggs are easily distinguished from those 

 of Rissa tridactyla by their greater gloss, and the small excrescences do not 

 lie quite so crowded, and are a little more flattened than they usually are in 

 the last-mentioned species. 



