NATURAL SCIENCES OF PHILADELPHIA. 133 



Lestris parasitica, Illiger, Prodromus, 1811, 273. Tetmninck,* Man. Ornith., 

 1820, ii. 796, (duse species confusae sunt.) Faber, Prodromus Island. 

 Orn., 1822, 105, (Nonne duse species confusae ?) Brehm, Naturg. Europ. 

 Vog., 1823, 744. Kaup, Sk. Ent. Eur. Thierw., 1829, 47. Lesson, 

 Traite d'Ornith., 1831. 61(3. 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 setate 

 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, (nee 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 1S40, (pp. 493, 499, 

 500,) where he recognizes the two species and describes them accurately: but unfortunately tall*) 

 the parasitica, " Jiichardsoni," and the Buffoni, " parasitica." 



1863.] 



