AERONAUTES. 369 



Regarding the birds of Inscription Rock, there can, as we have already said, be 

 hardly a doubt, for both Dr. Coues 2 and Mr. Henshaw * have seen them there, with 

 full knowledge of the birds they were observing. We conclude, therefore, that the 

 names saxatilis and melanoleucus refer to one and the same species. 



The accounts of the habits of this Swift agree in most points, and are in full accord 

 concerning the features of the localities in which alone it is to be found : these are 

 gorges of the mountains with rocky precipitous sides, in the fissures and clefts of which 

 the birds reside. Both Dr. Coues and Mr. Henshaw speak of the abundance of this 

 species in Utah, Colorado, New Mexico, and Arizona, and as congregating in suitable 

 places where the fissured cliff's afforded them suitable roosting- and breeding-places. 



The presence of A. melanoleucus in Mexico rests upon the rather doubtful evidence 

 of two skins in the British Museum ^^, said to have come from that country, and the 

 statement by Sumichrast ^ that he believed he recognized it flying about the mountains 

 of Orizaba. There can, however, be little doubt that it is to be found in suitable 

 places in Mexico, as in the countries further to the northward. 



In Guatemala we only met with it in one locality, a gorge of the Rio Guacalate 

 between the villages of Dueiias and Ciudad Vieja, at an elevation of about 5000 feet 

 above sea-level ', a fissured precipice of igneous rock on one side of the valley har- 

 bouring a good many individuals. During the daytime some of the birds of this colony 

 might usually be seen soaring high in the air over the valley, others would be hidden 

 in the crevices of the rock, keeping up a continuous chatter. Every now and then one 

 or two would descend from the flock in the air and enter a crevice with the utmost 

 rapidity ; again others would dart out and join their companions in their flight. 



Owing to the inaccessibility and narrowness of the fissures frequented by birds of 

 this species their nests and eggs have not yet, so far as we know, been obtained. 

 Dr. Coues states ^ that they breed on the face of high perpendicular clifls, gluing their 

 nests to the sides ; and, again ^, that they were observed evidently nesting in the rocks, 

 but he could not say whether they built against the open rocks or in the crevices, 

 though they certainly did so upon the face of the cliffs. This account is not clear, 

 and it is not fully supported by Mr. Henshaw, who says * that on several occasions he 

 found colonies breeding in the faces of the cliff's ; the inaccessibility of the crevices they 

 had chosen for their retreats proved an insurmountable obstacle to any attempt to spy 

 out their domestic arrangements. 



Our own observations in Guatemala, which apply to cliffs of apparently much less 

 elevation than those visited by Dr. Coues and Mr. Henshaw, lead us to conclude that 

 the nests are placed inside the crevices and not against the face of the rock. We 

 visited the Guacalate colony in several months of the year (in February, July, and 

 November), and we never saw any trace of a nest outside a fissure. Debris from inside 

 one of the most frequented crevices consisted of feathers and pieces of dry grass, the 

 latter probably brought for nest-building. 



BIOL. CENTE.-AMER., Aves, Vol. II., January 1893. 47 



