IN his "Check-List of Birds of the World" James L. Peters (1940: 236) follows Ridgway and Hellmayr in listing Chaetura vauxi, Chaetura richmondi, and Chaetura gaumeri as distinct species, in spite of the fact that other able present-day workers have called them "merely repre- sentative forms" of the same species (see, in particular, Griscom, 1932: 196). The writer has been obliged to study these three forms carefully in identifying recent collections from Mexico, and he is now convinced that they are conspecific. There is no escaping the fact that they look alike. Their behavior, nesting habits, and call notes are said to be much the same. They are all essentially Middle American, even the northward ranging, strongly migratory vauxi returning to its tropical ancestral home for the winter months. The ranges of gaumeri and richmondi probably adjoin in Campeche and Quintana Roo, since no treeless plain, high sierra, or other barrier appears to exist between them. As for richmondi and vauxi, or gaumeri and vauxi, though the present known breeding range of the latter is, in either case, far removed from that of the former, it is quite conceivable (a) that vauxi, in pushing northward, has only recently become truly isolated or (b) that further work in the Rocky Mountains and the Sierra Madre will reveal the fact that a chain of breeding populations actually connects the three forms. The primary purpose of the present paper is to announce the discovery of one such breeding population, a form that is close to gaumeri and between vauxi and richmondi in color and size. This new bird has been called "richmondi" by Phillips (1911: 77), Ridgway (1911: 720), and others. It has also been called "vauxi" by no less able an ornithologist than Peters who, in examining our material, perceived it to be darker and smaller than topotypical specimens of "Cypcelus Vauxi" (type locality Columbia River ----- Fort Vancouver, Washington) and who may even have suspected it of being a race of the northwestern United States bird. Need more be said as to its linking C. v. richmondi and C. v. vauxi? Since no name thus far given to any Middle American swift appears to be available, the author suggests Chaetura vauxi tamaulipensis, subsp. nov. T3/4,E.--Breeding male (testes greatly enlarged) in unworn plumage, collection of George M. Sutton, No. 9601; Rancho Rinconada, along the Sabinas River, a mile west of the main Mexico City highway, at an elevation of about 500 feet, in the vicinity of the village of G6mez Farias, southwestern Tamaulipas, April 15, 1941; collected by George Miksch Sutton. 232 THE WILSON BULLETIN December, 1941 Vol. 53, No. 4 SUBSPECIFIC CHARACTERs.--SimiIar to Chaetura vauxi vauxi in wing-length and body-size, hence larger than C. v. richmondi (from southern Veracruz, Costa Rica, Guatemala, and interlying parts of Central America), C. v. gaumeri (from Yucatan), and C. v. ochropygia (from the Azuero Peninsula of Panama). Darker than C. v. vauxi, es- pecially on the upper parts, belly, under tail coverts, and basal part of the throat plumage; crown, back, and wings noticeably more glossy, the shine being rather strongly greenish; and eyebrow without fine whitish line that is usually so distinct in C. v. vauxi. Less blackish than C. v. richmondi above; wings duller, with greenish rather than blue or bluish green gloss; and rump and under parts somewhat lighter. Less blackish on back, crown, and wings even than C. v. gaumeri, and more brownish throughout belly, under tail coverts, and rump. Larger and noticeably darker-rumped than C. v. ochropygia, a far-removed form that it would hardly be expected to resemble at all closely. RAr..--Breeds in heavily wooded lowlands, along streams, in southwestern Tamaulipas, southeastern San Luis Potosi, and probably contiguous parts of Hidalgo, northern Veracruz, and southeastern Nuevo Leon. May be migratory, since one November specimen from Guatemala has been examined. Probably intergrades with C. v. gaumeri and C. v. richmondi. RxARrZs.--There are some misconceptions concerning certain races of Chaetura vauxi. Two of these have to do with C. v. gaumeri. Through the courtesy of Dr. Josselyn Van Tyne the author has been able to examine several freshly plumaged specimens of this race taken recently at Chichen Itzg, Yucatan. These are, to be sure, less blackish on the crown and back, and less bluish on the wings than strictly comparable C. v. richmondi from Costa Rica; but the rump is not strikingly light by comparison, and there is little evidence in support of calling the race a pale one. Furthermore, in all freshly plumaged birds the tail is fully spined. There are several such well-spined individuals in the University of Michigan Museum of Zoology collection. The spines apparently are subjected to much abrasion in the limestone wells which the swifts in- habit, and worn specimens have given rise to the belief that the tail of C. v. gaumeri is spineless. A third misconception has to do with certain Guatemalan specimens that have been called by Griscom (1932: 196) "obvious intermediates" between C. v. vauxi and C. v. richmondi. The author, who has examined two of these very birds, feels that the Finca Carolina male, which Gris- corn describes as "nearer richmondi in size, nearer vauxii in color" (Amer. Mus. Nat. Hist. No. 393,915) is clearly an example of C. v. vauxi, and not in any genetic sense of the word intermediate. It is a molting bird, with badly worn outer primaries, and therefore wholly unreliable wing-length (111 mm.). The incoming remiges are naturally dark and glossy, just as they are in freshly plumaged or molting United George M. NEW RACE OF CHAETURA 233 Sutton States C. v. vauxl. The San Lucas male, said to be "nearer richmondi in color, near vauxii in size" (Amer. Mus. Nat. Hist. No. 393,928), agrees perfectly with the type series of C. v. tamaulipensis and must, for the present, be considered a Guatemala record of the race; but it should not be called intermediate between C. v. vauxi and C. v. rich- mondi, for such a designation implies an actual commingling of the two forms during the breeding season. Migrating C. v. vauxi probably move northward and southward to the west of the breeding grounds of C. v. tamaulipensis, so transient vauxi-like birds seen in eastern Mexico are likely to be tamaulipensis. Wintering swifts will have to be identified with great care, however, in view of Lowery's recent discovery of C. v. vaux in winter in Louisiana (1939). MEASUREMENTs.--Type: wing, 111 mm.; tail, 35. Topotypical male: wing, 111; tail, 37. Topotypical females: wing, 115, 109; tail, 33.5, 32. Female from Matlapa, near Tamazunchale, San Luis Potosi: wing, 113; tail, 38.5. Female from San Lucas, Guatemala: wing, 114; tail, 37. Male from Guiaves, Tamaulipas: wing, 113.5; tail, 38. Female from Carricitos, Tamaulipas: wing, 111; tail, 40. Average of males: wing, 111.8; tail, 36.6; of females: wing, 112.4; tail, 36.2. Wing meas- urements are of the chord of the folded manus. ACNOWLEDGEMENTs.--The valuable assistance of Mr. James L. Peters and Dr. Josselyn Van Tyne has already been mentioned. Mr. Adriaan J. van Rossem was good enough to lend the author a useful series of C. v. vauxi (including virtual topotypes from western Wash- ington) from the Dickey Collections. The American Museum of Nat- ural History cooperated by lending Guatemalan and Costa Rican ma- terial. Mr. George H. Lowery, Jr., was particularly helpful in lending all of his freshly plumaged, carefully washed C. v. vauxi taken recently at Baton Rouge, Louisiana. REFERENCES CITED GRISCO/f, LUDLOW 1932 The Distribution of BirdsLife in Guatemala. Bull. Amer. Mus. Nat. Hist., 64. LOWERY, GEORCE H., JR. 1939 Vaux's Swift in Louisiana. Wilson Bulletin, 51: 199-201. PETERS, JAMES L. 1940 Check-list of Birds of the World, Vol. 4. Harvard University Press, Cambridge. PaILLIPS, Joas C. 1911 A Year's Collecting in the State of Tamaulipas, Mexico. Auk, 28: 67-89. RIDGWA3/4, ROBERT 1911 The Birds of North and Middle America. Bull. U.S. Nat. Mus., No. 50, part 5. CORNELL UNIVERSITY, ITHACA, NEW YORK.