1863.] SPINE-TAILED SWIFTS. 101 



Readily distinguishable from C. pelasyia by its smaller size, paler 

 rump, nearly white throat, and lighter under parts. C. poliura, 

 which somewhat resembles it, is blacker on the back and head, and 

 much darker below. 



6. Ch^tura poliura. 



Cypselus poliourus, Temm. Tabl. Meth. p. 78 (ex Buff. PI. Eul. 

 726. f. 2). 



Acanthylis cinereicauda, Cass. Proc. Acad. Philad. 1850, p. 58. 

 Cypselus pelasgius, Max. Beitr. iii. p. 347. 

 Acanthylis oxyura, Burm. Syst. Ueb. ii. p. 366. 

 Acanthylis poHoura, Bp. Consp. p. 64. 

 Chcetura poliura, Sclater, Cat. Am. B. p. 283. 



Supra (Bneo-nigra; uropygio et tectr. caudce sup. fuliginosis ; 

 subtus fuliginosa, gutture albicantiore. 



Long, tota 4-2, alee 4-8, caudse 1-8. 



Hab. Cayenne and Brazil. 



Mus. P. L. S. 



One of the specimens of this species in my collection is said to be 

 from Brazil ; but the other is certainly from Cayenne, and Buffon 

 describes the species as from that country. I have compared my 

 examples with the type of Mr. Cassin's A. cinereicauda, and can 

 vouch for their identity. It is perhaps doubtful whether Buffon's 

 figure was not really intended for C. pelasgia, in which case this 

 bird should bear Mr. Cassin's name — cinereicauda. 



7. Ch^tura cinereiventris. (PI. XIV. fig. 1.) 



Cypselus acutus. Max. Beitr. iii. p. 351 (nee auct.). 

 Acanthylis spinicauda, Burm. Syst. Ueb. ii. p. 366. 

 Chcetura cinereiventris, Sclater, Cat. Am. B. p. 283. 



^neo-nigra ; uropygio et corpore subtus cinereis ; crisso nigri- 

 cante. 



Long, tota 4*3, alae 4-2, caudse 2-8. 



Hab. South-eastern Brazil. 



Mus. P. L. S. 



The cinereous uropygium and body beneath render this Brazilian 

 bird very easily recognizable on comparison with its congeners, though 

 it has been hitherto always confounded with one or other of them. 



8. ChjEtura spinicauda. 



Cypselus spinicaudus, Temm. Tabl. Meth. p. 78 (ex Buff. PI. Enl. 

 726. f. 1). 



Hirundo pelasgia, var.. Lath. Ind. Orn. ii. p. 581. 



Acanthylis spinicauda, Boie, Isis, 1826, p. 971; Bp. Consp. p. 64. 



Chcetura spinicauda, Sclater, Cat. Am. B. p. 283. 



Nigra ; fascia uropygiali alba ; subtus albicanti-fuliginosa ; pec- 

 tore indistincte nigra vittato. 

 ■ Long. 37, alse 3-9, caudse 1-6. 

 Hab. Cayenne. 

 Mus. P. L. S. 



