NATURAL SCIENCES OF PHILADELPHIA. 
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Lestris parasitica, Illiger, Prodromus, 1811, 273. Temminck,* Man. Ornith., 
1820, ii. 796, (duse species confusse sunt.) Faber, Prodromus Island. 
Ora., 1822, 105, (Nonne duse species confusse ?) Brelim, Naturg. Europ. 
Yog., 1823, 744. Kaup, Sk,. Ent. Eur. Thierw., 1829, 47. Lesson, 
Traite d’Ornith., 1831. 616. Schinz, Europ. Fauna, 1840, i. 390. Bona- 
parte, Conspectus Avium., 1856, ii. 208. 
Lestris Richardsonii , (“Swains.”) Temminck, Man. Orn., iv. 1840, 499. 
(Sed non Swains, quae potius species distincta.) Nuttall, Man. Ornith., 
ii. 1834, 319. Audubon, Ornith. Biograph., iii. p. 503 ; Audubon, 
Synopsis, 1839, 332. Audubon, Birds America, 1844, vii. 190, pi. 452. 
Giraud, Birds L. I., 1844, 367. Schinz, Europ-. Fauna, 1840, i. 392. 
Thompson, Nat. Hist. Ireland, 1851, iii. 394. 
Cataractes Richardsoni, Macgillivray, Man. Orn., ii. 1842, 257. 
Catharacta coprotheres , Briinnich, Orn. Borealis, 1764, 38, No. 138. In aetate 
fusco-unicolore . ) 
Lestris coprotheres, Des Murs, Traite d’Oologie Ornith., 1860, 551. 
Lestris parasitica var. coprotheres, Bonaparte, Consp. Av., 1856, ii. 209. 
Stercorarius — , Brisson, Ornith., vi. 1760, (nomen specificum nullum.) 
Stercorarius crepidatus, Vieillot, Nouv. Diet. d’H. N., xxxii. 1819, 155. (Sed 
non Larus crepidatus , Gmel., Lath., qui potius juvenis Lestris pomarinus, 
Temm.) 
Stercorarius cepphus , (“Leach,”) Swains, et Richardson, F. B. A., ii. 1831, 
p. 432. Stephens, Shaw’s Gen. Zool., 1825, xiii. 211, pi. 23. Degland, 
Ornith. Europ., 1849, ii. 295, (nec auct.) 
Stercorarius parasiticus , Selys-Longchamps, Fauna Belg., 1842, 155. Gray, 
Genera Birds, iii. 1849, 652. Lawrence, Gen. Rep. Birds N. A., 1858, 
839. Coues, Proc. Acad. Nat. Sci. Philada., 1861, p. 243. 
Lestris crepidata, Degland, “Mem. Soc. Roy. de Lille, 1838, 108.” Juvenis. 
Schinz, Europ. Fauna, 1840, i. 390, Juvenis. 
Habitat. — Coast of America and Europe, more particularly in higher lati- 
tudes. Interior of Arctic America. 
Pursuing the question of the general “theory of variation” in this genus, 
it may be well to examine closely the various stages of this its typical spe- 
cies. The exceedingly rich series in the Smithsonian collection enables me 
to trace it through all its variations. 
Young of the Year in August.— Size considerably less than that of the 
adult, form every way more delicate. Wings more than an inch shorter ; 
bill and feet much slenderer and weaker. Bill in some specimens light bluish 
horn, in others greenish olive, the terminal portion brownish black. Tarsi 
and greater part of the toes yellow. The bird is every where rayed and 
barred with rufous and brownish black. On the head and neck the rufous is 
of a very light ochraceous tinge, and is by far the predominating color ; the 
dark only appearing as a delicate line along the shaft of each feather. There 
is an aggregation of the brown into a spot at the anterior canthus of the eye. 
Proceeding down the neck to the back, the longitudinal lines become larger, 
and gradually spread wider and wider, until between the shoulders they 
occupy the whole of each feather, except a narrow border of rufous ; which 
latter is of a deeper tint than on the head. Passing down the throat to the 
breast, the rufous becomes decidedly lighter, — almost whitish, — while the 
brown, which on the throat exists only as a light longitudinal line, change s 
on each feather to transverse bars of about equal width with the light rufou s 
bars with which it alternates. This pattern prevails over the whole unde r 
* This is a combination of parasitica and Buffoni, as shown by the description and indescrimi- 
nate citation of synonyms. This error Temminck corrects in his edition of 1840, (pp. 493, 499, 
500,) where he recognizes the two species and describes them accurately : but unfortunately calls 
the parasitica, “ Richardsoni,” and the Buffoni, “ parasitica .” 
1863.] 
