458 THALASSIDROMA WILSONII. 



needle. The anterior toes are long, very slender, obscurely 

 scutellatc ; their claws slightly arched, rather depressed, 

 acute. The interdigital webs arc very narrow, and deeply 

 emarginate. 



The bill and feet are black, but on each of the webs is an 

 elongated yellow patch. The general colour of the plumage 

 is greyish-black, tinged with brown, the lower parts of a 

 sooty brown ; the quills and tail brownish-black ; the outer 

 secondary wing-coverts brownish-grey, as are four of the 

 secondary quills, which are also externally margined with 

 white. The upper tail-coverts, some of the feathers on the 

 rump, the sides of the abdomen, and the lateral inferior tail- 

 coverts, with the basal part of the tail-feathers, are Avhite. 



Length to end of tail 7| inches ; extent of w'ings 16 ; 

 wing from flexure 6 ; tail 2|; bill along the ridge -^; along 

 the edge of lower mandible -^ ; tarsus 1-j^ ; hind toe and 

 claw -^ ; second toe, \%, its claw j^- ; third toe \^, its claw 

 -j^ ; fourth toe 1, its claw y^-. 



Female. — The female is similar to the male. 



Habits. — This species, named by the Prince of Canino, 

 in honour of the celebrated Scoto-American ornithologist, is 

 represented as breeding on various parts of the eastern coast 

 of North America, and as occurring plentifully on the 

 Atlantic Ocean, although little is known as to the extent of 

 its distribution. Mr. Audubon states that he has rarely seen 

 it on the Gulf of Mexico, and never farther northward than 

 lat. 51 degrees, while to the eastward few were observed 

 by him beyond the Azores. The following extract from the 

 Ornithological Biography of that excellent observer will afford 

 a sufficient idea of its habits : — " AVilson's Petrel breeds on 

 some small islands situated off the southern extremity of 

 Nova Scotia, and called ' Mud Islands,' but which are formed 

 of sand and light earth, scantily covered with grass. Thither 

 the birds resort in great numbers about the beginning of 

 June, and form burrows of the depth of two or two and a half 

 feet, in the bottom of which is laid a single white egg, a few 

 bits of dry grass, scarcely deserving the name of a nest, having 



