NATURAL SCIENCES OF PHILADELPHIA. 137 



the feathers'before and below the eye, and on the sides of the bill, being of 

 this color. Neck all round, but especially the sides of the head and the 

 peculiarly formed feathers on the latero-nuchal region, light straw yellow. 

 Whole upper parts, with upper wing and tail coverts deep slate ; which, on 

 the primaries, secondaries, lateral tail feathers and distal half of central 

 pair, deepens into a pure lustrous brownish black. Under surface of wings 

 and tail deeper slate than the back, but not so deep as the upper surfaces. 

 Chin, throat and upper breast white ; gradually becoming obscured with 

 dusky plumbeous, which (feepens posteriorly, so that the abdomen and under 

 tail coverts are nearly as dark as the back. Rhachides of first two or three 

 primaries pure white, deepening into brownish black at their extreme apices; 

 of the other primaries, and of the tail feathers (including the central pair} 

 brown, except just at the base, deepening into quite black terminally. The in- 

 ferior surfaces of all the rhachides are white for nearly their whole length. 



Length of culmen 1*15 inches; gape 1-70; cere -60; unguis about the 

 same; gonys -30 ; from feathers on sides of bill to tip -90; wing 12-50 ; tail 

 6-25 ; central pair 14-00 to 16-00 ; the projection 8-00 to 10-00 inches ; tibiae 

 bare -75 ; tarsus 1-60; middle toe without claw 1-40. 



Habitat. Sea coasts of America and Europe, particularly in the higher 

 latitudes. Interior of Arctic America. (Kennicott.) 



The changes of plumage of this species are strictly homologous with those 

 of S. parasiticus ; and it is therefore quite unnecessary to present them in this 

 connexion. 



As before remarked under head of parasitica, it is exceedingly difficult, if 

 not quite impossible, to determine positively to what species the u parasitica" 

 and ' cepphus" of the older authors refer. This confusion is occasioned 

 partly by the brief and vague diagnoses given, and partly by the fact that the 

 two species were really confounded by authors (except Brisson) until com- 

 paratively quite a late period. Even so late as 1820 Temminck does not 

 separate the two : his description applies to either, and the synonyms of both 

 are indiscriminately adduced. From which state of things it results that 

 nearly all the older names and citations may be without difficulty referred to 

 either species. This in effect has been really done ; some authors, for ex- 

 ample, considering Brunnich's or Linnaeus' parasitica to be the long-tailed 

 species, and others holding a contrary opinion, until the identification of 

 these names has become almost a matter of choice, or rather of tacit agree- 

 ment among ornithologists. This is the more to be regretted since on it de- 

 pends the question whether the common or the long-tailed Jager is to be called 

 parasiticus. A glance at the synonymy of the species will show that authors 

 have been about equally divided on these points. Before the introduction of 

 11 Richardson?' by Swainson, the common Jager was usually called "para- 

 sitica;" but after the adoption of this name " Richardson? 1 by Temminck, for 

 the common Jager, the name parasitica was for some years almost univer- 

 sally applied to the long-tailed species. In the year 1819, or thereabouts, 

 the name of Buffoni was proposed by Boie for the long-tailed species, and 

 was adopted by many writers ; while others had recourse to Brisson's old 

 name " longicaudatus." Within the last few years, however, the name "para- 

 sitica" has again reverted to the common Jager, while the other species has 

 been usually called " cepphus" after Brunnich. This identification of Brun- 

 nich's name is adopted by Gray, Bonaparte, and other writers. Our reasons 

 for rather referring it to the Stercorarius pomarinus will be found under the 

 head of the latter. 



Granting, as it is undoubtedly wisest to do, that th.z parasitica of Brilnnich, 

 Linnaeus and Gmelin, is really the common short-tailed^ Jager, it still remains 

 an open question to which species we are to refer the Larus parasiticus of 

 Latham. I incline to the opinion that it is based upon the long-tailed spe- 

 cies, for the following reason : Although the diagnosis is brief and unsatis- 



1863.] 



