374 CYPSELIDA. 
Swift at Villa Alta in Oaxaca, but no specimens, so far as we know, were included in 
MM. Sallé’s and Boucard’s collections. 
Nor have we any tidings of it from any of the more northern or western parts of the 
Republic of Mexico. 
In Guatemala we believe it to be pretty generally distributed, and we observed it at 
different places from the sea-level at San José de Guatemala to as high as the mountain 
ridge above Calderas on the Volcan de Fuego, an altitude of 8300 feet. 
In the rainy season flocks of this Swift were frequently to be seen flying high over 
the plain of Duefias, occasionally descending to within gun-shot, when a few specimens 
could be secured. A roosting-place of a flock of these birds was in the rocks over 
which the Guacalate formed a cascade near the village of Ciudad Vieja. On one 
occasion a number of these birds which had been observed flying over the valley 
suddenly descended and disappeared behind the fall. 
2. Chetura semicollaris, 
Acanthylis semicollaris, De Sauss. Rev. Zool. 1859, p. 118’. 
Chetura semicollaris, Scl. P. Z. 8. 1865, p. 609?; Scl. & Salv. Ex. Orn. p. 103, t. 52°; Sumichrast, 
Mem. Bost. Soc. N. H. i. p. 562*; Herrera, Apuntes de Ornit. p.15°; Hartert, Cat. Birds 
Brit. Mus. xvi. p. 479°. 
Hemiprocne semicollaris, Sumichrast, La Nat. v. p. 2507. 
~ Fuliginoso-nigra, capite toto et gutture vix pallidioribus, fascia transversa angusta nuchali alba. Long. tota 
circa 9-5, ale 9-2, caude 2-9. (Descr. exempl. typ. ex Mexico. Mus. Brit.) 
Hab. Mexico}, San Joaquin near the capital (Sumichrast‘). 
Several specimens of this large Swift were killed near Mexico city by Sumichrast 
when he was in company with M. H. de Saussure in 18567. ‘These birds were described 
by the latter naturalist in 1859 1, and one of the typical specimens passed into Mr. Sclater’s 
possession and was figured in ‘ Exotic Ornithology’®. This last-named bird, which is 
now in the British Museum, is the only one we have seen. 
Of the species very little is known; Sumichrast does not seem to have met with it 
again, and Herrera speaks of it as probably a bird of accidental occurrence ®, Neither 
Sallé nor Boucard notice it; nor have we any tidings of it in the large collections of 
Richardson, Lloyd, and others recently formed in various parts of Mexico. 
C. semicollaris is most nearly allied to C. zonaris, but may readily be distinguished 
from that species by its large size and by the white collar being restricted to the back of - 
the neck, and not forming a complete ring round it, as is the case in the allied form. 
b. Minores: torques cervicalis nullus. 
8. Chetura pelagica. 
Mirundo pelagica, Linn. Syst. Nat. i. p. 192 (1758)*. 
Chetura pelagica, Baird, Brew., & Ridgw. N. Am. Birds, ii. p. 432?; Coues, Birds N. W. p. 267°; 
Salv. Ibis, 1889, p. 367°; Hartert, Cat. Birds Brit. Mus. xvi. p. 480°. 
