80 PROCEEDINGS OF THE ACADEMY OF 



family Pro cell aridce of Linnaeus' genus Procellaria, and proceed to separate 

 the component genera according to the now generally received definition of 

 a "genus ;" then Procellaria must be restricted to pelagica and its congeners, 

 and other names be found for the remaining generic groups ; there are few 

 points of synonymy, involving a Linnean name, more clearly demonstrated 

 than this. 



The first synonym of Procellaria that I have met with is Hydrobales, Boie, 

 Isis Von Oken, 1822, p. 5G2. This has pelagica as its type. This is not, 

 however, to be confounded with Hydrobata, Vieillot, 1816, wilich is a genus 

 of Turdida;, with Slurnus cinclus, L. as type. 



The second synonym of the genus is Thallassidroma, Vigors, Zoological 

 Journal, Vol. ii. for October. 1825, page 405. Although based upon pelagica, 

 and therefore an entire synonym of Procellaria, Linn., this name has become 

 most firmly established, not only as an appellation for this genus, but also 

 for all the Stormy Petrels indiscriminate^'. It will be evident, I hope, from 

 what has just been said, that not only is the name quite untenable for the 

 present genus, but that it cannot be used with propriety in any connection. 



The number of species composing this genus is a little uncertain ; partly 

 in consequence of unusual variations to which pelagic i seems subject; and 

 partly because the indications of many comparatively recently described 

 species are not explicit enough as regards proportions, etc., to admit of a 

 definite reference to their proper genus. I will first notice pelagica and its 

 kindred species, and then consider those species which seem to fall most 

 laturally in this genus. 



1. Procellaria pelagica, Linnaeus. 



Syst. Nat. ed. vi., 1746 ; nee. Wils. Amer. Ornith. vii. p. 90. Hgdrobatet 

 pelagica, Boie, Isis, 1822, p. 562. Thallassidroma pelagica, Vigors, Zool. Journ. 

 ii., 1825, p. 405, et auctoruru fere omnium post. A. D. MDCCCXXV. Above 

 glossy brownish black, below more fuliginous the under tail coverts, however, 

 of the former color, and very long, reaching sometimes to bej'ond the tips of 

 the rectrices themselves. The superior caudal tectrices are pure white, ter- 

 minated, however, with equally well defined black tip3. The white of the 

 crissum is less pure and well defined; and that of the under tail coverts is 

 much interrupted with blackish. The inferior alar tectrices and the axillary 

 feathers are variegated with light touches of dull white. 



This species apparently varies to an unusual extent in size, especially ae 

 regards length of wing. Specimens before me measure about 4.} inches from 

 the carpal joint. Dr. Schlegel says, " aile 4 pouces a 4 pouces 6 lignes." 

 Mr. Lawrence says " wing five inches." These variations, and doubtless cor- 

 responding discrepancies in other dimensions, have been the cause of the 

 founding of several species ; either entirely nominal, or at most constituting 

 races of the same parent stock. Omitting entirely to notice Brehm's multi- 

 farious "species" [sic!] those most entitled to consideration are the fol- 

 lowing : 



? 2. Procellaria tethys, Bonaparte. 



Comptes Rendus, 1S54, xxxviii. p. 662; et 1856, xlii. f. 769, et Consp. Av. 

 ii., 1856, p. 197. From the Gallapagos Islands. This typical Procellaria 

 is exceedingly closely allied to pelagica ; but differs from it in wanting the 

 black tips of the superior caudal tectrices, which are always found in the 

 latter. It is also said to be somewhat smaller, and to have less markedly 

 the transalar fascia. 

 ? 3. Procellaria luodbris, Natterer. 



Acta Ital. Medio!., 1844. "Ex oceano Mcred." This species (if it be really 

 one), differs from the typical pelagica in being somewhat larger, and in having 

 a more robust bill. It would appear also that there is less of whitish upon 

 either surface of the wing, and upon the under tail coverts. The upper tail 



[Murch 



