830 U. S. P. R. R. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 
The above is a copy of Mr. Gray's description of this species; he states that " in form it 
agrees best with Thai, furcata, hut the coloration differs much in several particulars." 
Thalassidroma, Vigors. 
THALASSIDROMA LEACHII, Bon. 
Leach's Petrel. 
Procellaria leachii, Temm. Man. II, 1820, 812. | 
Thalassidroma leachii, Bon. Syn. 1828, No. 309.— Ib. Consp. II, 1855, 193.— Nutt. Man. II, 1834, 326.— Aud. 
Orn. Biog. Ill, 1835, 434.— Ib. Buds Am. VII, 1844, 219 ; pi. cccclix. 
Procellaria bullockii, Flem. Br. Anim. 1828, 136, No. 219.— Vigors 
? " Procellaria leucorrhoa, Vieillot." Bon. 
Sp. Ch. — The plumage generally is sooty brown, darker on the crown ; primaries and tail brownish black ; wing coverts and 
inner secondaries ashy gray ; rump, feathers of the sides adjoining it, and outer lower tail coverts, white ; bill black ; iris dark 
brown ; tarsi and feet black. 
Length, 8 inches ; wing, 6| ; tail, 3 ; bill, § ; tarsus 1. 
The female differs only in being rather smaller. 
Hab. — Atlantic coast from Massachusetts to Baffin's Bay. 
This is larger than Wilson's petrel, and has a much stronger hill ; it may be readily known 
from it by its forked tail, and the interdigital webs being entirely black. 
List of specimens. 
Locality. 
Whence obtained. 
Original No. 
Coast of New York 
George N. Lawrence 
1018 
Atlantic coast. 
S. F. Baird 
....do 
THALASSIDROMA MELANIA, Bonaparte. 
The Clack Stormy Petrel. 
Procellaria melania, Bon. Comptes Rendus, Ac. Sc. XXVIII, 1854, 662. 
Thalassidroma melania, Bon. Cons. Av. II, 1855, 196. 
11 ? Procellaria fuliginosa, Lath. Not of Kuhl." Bon. 
" ? Procellaria scapulata, Brandt." 
Sp. Ch. — Entire upper plumage black ; wing coverts wholly black ; below fuliginous ; wings long ; tail short, but deeply 
forked. 
Hab. — Coast of California. 
It somewhat resembles Thai, leachii, but is distinguished from this as well as all its congenere 
by the absence of white on the rump, crissum, and on the wing coverts. 
