noble: the resident birds of Guadeloupe. 371 



Lafresnaye (Rev. zool., 1844, p. 168) in his original description of 

 Procellaria diabolica, referring to the larger specimens, says: — 



"Une espece de Petrel, le Petrel Diable, du pere Labbat, Diablotin a 

 la Guadeloupe, Procellaria diabolica L'Herminier, qui y arrive vers la 

 fin de septembre, y niche en decembre dans les Falaises; une seconde 

 espece, en tout semblable de plumage a celle-ci, et n'en differant 

 que par une taille moindre, y arrive a une autre epoque, niche dans les 

 memes falaises, mais a un etage different en hauteur, 'ce qui les fait 

 distinguer a la Guadeloupe par les noms de Petrels des hauts et Petrels 

 des bas. Ces deux oiseaux seront pris pour la meme espece par tons 

 les ornithologistes qui les possederont sans renseignements sur leurs 

 moeurs. Cependent M. L'Herminier les regarde comme constituant 

 deux especes bien distinctes, differant essentiellement de moeurs et 

 d'epoque de passage. Mais n'anticipons pas sur les futurs documents 

 que nous promet notre savant collegue, et qui auront un bien autre 

 interet sous sa plume et racontes de visu." 



The two pairs of Black-capped Petrels from the Lafresnaye collec- 

 tion are different from each other not only in size but in coloration 

 and in shape of the nostril tubes. The smaller ones have the grey of 

 the cap extending down the back of the neck and not terminating 

 abruptly on the nape as in the larger birds, and the nostril tubes of 

 the smaller birds are higher and end more abruptly than those of the 

 larger specimens. In this respect as also in size the smaller birds are 

 similar to Aestrelata jamaicensis. Each pair represents, I believe, a 

 distinct species of Aestrelata. 



Which species, then, is Aestrelata haesitata? This is a difficult 

 question to decide because of the uncertainty of the original descrip- 

 tion. Kuhl (Beitrage zur zoologie, Frankfurt, A. M., 1820, p. 142) 

 described a petrel "in Museo Bullokiano, nunc in Temminkiano" 

 and calculated his measurements in terms of the "pollex." 



If we assume that the pollex was the Frankfurt a. M. inch of that 

 time, as determined by the Bureau of Standards at Washington and 

 sent me by letter, it is then possible that Kuhl's specimen could be 

 referable to either of the Guadeloupe species under consideration or 

 better still to neither. Dr. Stejneger, however, recently told Mr. 

 Bangs that Kuhl was a student of Temminck and would very likely 

 have used the French system. Changing Kuhl's measurements 

 from French inches (Ridgway, Nomenclature of colors, 1886, pi. 17 

 note) into millimeters and comparing them with the measurements 

 of the Guadeloupe birds we find the figures more closely approximat- 

 ing the measurements of the small than of the large species. But 



