376 CYPSELIDZ. 
pallidior, abdomine quam guttur paulo obscuriore. Long. tota circa 4:0, ale 4:5, caude 1:55, (Deser. 
maris ex Mexico. Mus. nostr.) 
Hab. Nortn America, Western States from British Columbia southwards 5.—Mexico 
(de Saussure), Sierra de Mexico (Rébouch), Rio Seco near Cordova, Valley of 
Mexico’ (Sumichrast), Puebla (Mus. Brit.!°), Laguna del Rosario in Tlaxcala 
(f. Ferrari-Perez®), Guichicovi’, Tehuantepec (Sumichrast, in U. S. Nat. Mus.®) ; 
GuatTemaLa, Raxche®, Coban 11, Duefias, Alotenango and Tierra Caliente generally 
(0. 8. & F. D. G.); Honpuras (Dyson, in Mus. Brit.™); Nicaragua, Rio Escondido 
(C. W. Richmond, in U. S. Nat. Mus.) ; Costa Rica (Van Patten, in U. 8. Nat. Mus.). 
This species is a near ally of C. pelagica, but may be distinguished by its smaller 
size, the wing being on an average nearly an inch shorter ; the tarsi and toes, however, 
are relatively longer ; in colour it is generally paler. 
C. vauxi was discovered by Townsend in the Columbia river, where he found it 
common, breeding in the hollow trunks of trees, in the same manner as C. pelagica, and 
laying four white eggs!. The bird is now known to be widely spread in Western North 
America from Puget’s Sound to California. It occurs also in Mexico and Guatemala, 
and thence southwards to Costa Rica. In Guatemala we used to see it not unfrequently 
in the winter months flying over the open ground between the volcanoes of Agua and 
Fuego, and occasionally a flock would fly low enough to enable us to secure a few 
specimens. We also observed it in various parts of the department of Vera Paz. 
Though there can hardly be a doubt that these southern birds are simply individuals 
of C. vauxi in their winter-quarters, some attempts have been made to separate them 
as distinct. Thus Mr. Lawrence at one time referred a Duefias specimen to his 
C. gaumeri, and associated with it an example from Tehuantepec, and these birds he 
seems afterwards to have discriminated under the name of C. similis*. When due 
allowance is made for small individual differences in size, and for the wear and tear of 
the plumage, we do not think it possible to define these southern birds as distinct from 
the true C. vauzi. 
5, Chetura gaumeri. 
Chetura vauci, Lawr. (nec Townsend) Ann. Lye. N. Y. ix. p. 204°. 
Chetura gaumeri, Lawr. Ann. N. Y. Ac. Sc. ii. p. 2457; Boucard, P. Z. 8. 1883, p. 451°; Ridgw. 
Pr. U.S. Nat. Mus. vi. p. 415‘; Salv. Ibis, 1889, p. 367°; Stone, Pr. Ac. Phil. 1890, 
p. 206°; Hartert, Cat. Birds Brit. Mus. xvi. p. 4827. 
Chetura yucatanica, Lawr. Ann, N. Y. Ac. Se. iii. p. 156°. 
hetura peregrinator, Lawr. Ann. N.Y. Ac. Se. iii. p. 273°. 
C. vauxt similis, sed plerumque minor supra saturatior, abdomine et tectricibus subcaudalibus quoque obscu- 
rioribus. Long. tota circa 4-0, alee 4:2, caude: 1-4. (Descr. maris ex Cozumel I., Yucatan. Mus. nostr. ) 
* Probably the same bird is referred to by Mr. Ridgway as C. affinis (Pr. U. 8. Nat. Mus. ix, p. 158). We 
have not been able to find any description of it or of C. similis. 
