404 Mr. D. G. Elliot on the Trochilidae. 



the specimens given above ; and there is also a difference in 

 the length of wing between specimens from the Rio Napo. 

 It is therefore very evident that size, upon which the sup- 

 posed species was given a distinctive rank, is not to be re- 

 lied on any more than is a particular locality ; and therefore 

 it is impossible to keep the two separate, as there is not a 

 single other character to distinguish them apart. And I the 

 more readily relegate P. iolatu to tlie condition of a synonym, 

 as I do not understand wherein the study of ornithology is 

 advanced by the creation of species so closely related that 

 their distinctness cannot be discerned save by the assistance 

 of a pair of compasses. 



Petasophora thalassina. 



Trochilus thalassinus, Swains. Phil. Mag. 1827, p. 441. 



Petasophora thalassina, Gould, Mon. Troch. vol. iv. pi. 227 ; 

 id. Intr. Troch. (8vo ed.) p. 125. sp. 252. 



Hab. Mexico, Guatemala. 



A clearly marked species, most abundant in Mexico, but 

 extending its range into Guatemala. Resembling somewhat 

 in coloration P. anais, it is nevertheless a very much smaller 

 bird, and cannot be confounded with that species. 



Petasophora cyanotis. 



Trochilus cyanotis, Bourc. Rev. Zool. 1843, p. 101. 



Petasophora cabanidis, Heine, Journ. fiir Orn. 1863, 

 p. 182. 



Petasophora cyanotis, Gould, Mon. Troch. vol. iv. pi. 228 ; 

 id. Intr. Troch. (8vo ed.) p. 125. sp. 253. 



Petasophora cabanisii, Lawr. Ann. Lye. Nat. Hist. N. Y. 

 vol. ix. (18G8) p. 126. 



Hab. Venezuela, Costa Rica, Vcragua, Columbia, Ecuador, 

 Peru. 



A species with a very wide range, and apparently gene- 

 rally distributed in the different countries mentioned above. 

 The birds from Costa Rica, for which Heine proposed the 

 name of cabanidis (/. c), are, in my opinion, not specifically 

 distinct; and I have therefore placed this uame as a syji- 

 onyra. 



