121 



being more than a quarter part of the length of the shorter speci- 

 mens. The long external tail-feathers are also very variable in 

 length, being an inch and a half shorter in some specimens, with- 

 out any appearance of having been broken or worn. The only 

 diagnostic character that can be depended on in specimens of all 

 ages is the comparative length of the tarsi which are always 

 longer than the middle toe in the common species and never 

 longer in the arctic. The following table gives the comparative 

 length of the tarsus and middle toes of three specimens of each 

 species taken at random : — 



Tarsus 

 IMiddle toe . 



Lams argentatus. The favorite breeding-places of this bird, at 

 Manan and the neighboring islands, were the heaths, as they are 

 called by the inhabitants — dry, peaty bogs, covered with coarse 

 grass, scattered bushes, and dwarf firs. The nests were generally 

 placed so as to be sheltered by the firs or bushes, seldom in the 

 open heath. I should imagine, from Audubon's desci'iption, that 

 the number of nests on trees was greater at the time of his visit 

 than at present. This may be accounted for by the fact that the 

 breeding-places having been protected for some time by the 

 owners of the islands, the birds have not been so much disturbed 

 as formerly. On the Big Mud Island, near Yarmouth, they were 

 also found nesting on trees. More or less were found breeding 

 on all the islands we visited ; but everywhere with the exception 

 of the places mentioned, the nests were placed in the grass 

 among the rocks, or on the rocks themselves. The eggs found in 

 I)laces where the birds had probably not been disturbed were 

 about half hatched by the sixth of July. Dr. T. M. Brewer 

 states, in the 6th Vol. of the Journal, page 304, that the Larus 

 leucopterus is occasionally found breeding on the island near 

 Manan. As this bird is quite rare with us, and has always been 

 supposed to breed only on the shores of the Arctic Ocean, it was 

 an object of special search both to Mr. Cabot and myself ; but with 



* Millimetres. 



