290 
NEW-YORK FAUNA -BIRDS. 
GENUS THALASSIDROMA. Vigors. 
Bill shorter than the head, slender, feeble ; the upper mandible hooked ; lower pointed, de¬ 
flected at the tip, following the curvature of the upper ; mental angle obsolete. Nostrils 
in a single tube. Feet long and slender. Tarsus longer than the middle toe. Hind nail 
acute, sometimes obsolete. Tail square or forked, 
WILSON’S PETREL. 
Thalassidroma wilsoni. 
PLATE CXXIII. FIG. 271. 
(CABINET OF THE LYCEUM.) 
Proceilariapelagica. Wilson, Am. Orn. Vol. 7, p. 90, pi. 60. 
P. uilsoni. Bonaparte, Jour. Acad. Nat. Sc. Vol. 5, p. 229, pi. 9. 
Thalassidroma id. Id. Ann. Lye. N. Y. Vol. 2, p. 367. Nuttall, Man. Orn. Vol. 2, p. 322. Audubon, B. of 
A. Vol. 7, p. 223, pi. 460. Giraud, Birds of Long island, p. 370. 
Characteristics. Sooty black, with a reddish tinge. Nasal tube recurved. Tarsus 1’5. 
Wings extending beyond the slightly emarginated tail. Webs of the 
feet yellow, ending in black. Length, 6'0. 
Description. Upper mandible much hooked at the tip, O'5 long measured from above. 
First and third quills subequal, longer than the fourth ; second longest. Tarsus slender, 
smooth, 1*4 long. Naked space on the tibia O'7. Tail as if doubly emarginate ; the cen¬ 
tral pair, and external one on each side (0-2) longest. No vestige of hind toe or nail. 
Color. Upper and lateral tail-coverts and sides of the vent pure white; some of the seconda¬ 
ries tipped with white ; remaining parts sooty black. Webs of the feet yellow in their centres. 
Length, 6'5 - 7* 5. 
This little Petrel, or Mother Carey's Chicken, occurs commonly along our coast from 
Mexico to high northern latitudes. Breeds along the coast from Maine northwardly. One or 
two white eggs. Mr. Nuttall observed slight rudiments of a hind toe. Bonaparte is silent on 
the subject; but in those which I have examined, there was not the slightest vestige of toe or 
nail. Audubon describes the hind toe as conical, and so minute as scarcely to be perceptible. 
Geographical range between the 30th and 70lh parallels. 
