138 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



111. Myiarchus erythrocercus var. cooperi. 



fTyrannus cooperi, Kaup,* P. Z. S. Feb. 11, 1831, 51 (" Northern America and 

 Chili")- 



Myiarchus cooperi, Baird, Birds N. Am. 1858, 180 ; Catal. N. Am. B. 1859, 

 No. 132.— Scl., P. Z. S. 1859, 384; Catal. 1861, 232, No. 1428 (Mexico; 

 Guatemala).— Scl. & SALV.,Ibis, 1859, 122, 440; 1870, 837 (coast Hon- 

 duras).— Lawr., Ann. Lyc. N. Y. ix, 1869, 202 (Yucatan). 



Myiarchus crinitus, c. var. cooperi, Coues, P. A. N. S. July 2, 1872, 07 

 (Tehuantepec, Mazatlan, and Guadalajara, S. W. Mexico; Guate- 

 mala ?). 



Myiarchus crinitus var. cooperi, B. B. & R., Hist. N. Am. B. II, 1874, 331 

 (Mazatlan, Tehuantepec, and Yucatan). — Lawr., Bull. U. S.Nat. Mus. 

 No. 4, 1876, 28 (Tapana and Sta. Efigenia, Isth. Tehuantepec ; April; 

 Dec). 



fTyrannus mexicanus, Kaup,! P. Z. S. Feb. 11, 1851, 51 (loc.incog.). 



Myiarchus mexicanus, Lawr., Ann. Lyc. N. Y. IX, 1869, 202 (Yucatan); 

 Pr. Boston Soc. June 7, 1871 (Tres Marias Islands, W. Mexico). — 

 Sumichr., Mem. Boston Soc. I, 1869, 557, 560 (Vera Cruz ; hot re- 

 gion). 



Myiarchus yucatanensis, Lawr., P. A. N. S. Nov. 21, 1871, 235 (Yucatan, Mus. 



G. N. L.=M. mexicanus, Ann. Lyc. N. Y. IX, 1869, 202 !). 

 Myiarchus crinitus erythrocercus, Coues &- Sennett, Bull. U. S. Geol. and 



Geog. Surv. Terr. vol. iv, No. 1, Feb. 1878, 32 (Ft. Brown, Texas). 

 Alguacil de Moscas, Tres Marias vernac. (Jide Lawr., I. c). 



The occurrence of this variety within our limits was noted in the April 

 (1878) number of the Bulletin of the Nuttall Ornithological Club. Since 

 that time I have paid particular attention to the species, and find that it 

 is the only one of the genus that breeds on the Lower Rio Grande, which 

 it does in considerable numbers. • In its notes and habits, it appears to 

 closely resemble the M. crinitus. Seven identified sets of thirty two 

 eggs average .93 by .G6, the extremes being 1.03 by .73 and .82 by .65. 

 With one exception, no snake-skins were used in the construction of any 

 of these nests. They were composed of felted locks of wool and hairs, 

 and were placed not far from the ground, either in old Woodpeckers' 

 holes or in natural hollows in decayed trees or stumps. 



Note. — The eggs of the Myiarchus, as a genus, have a very remark- 

 able family resemblance. They are of a rounded-oval shape, in some 

 instances the relation of the axis to the diameter being as S\ to 74, and 

 averaging about 8J to 7. The ground-color varies from a light bulf to 

 a dark cream-color; over these are distributed two sets of markings, all 

 of them having a longitudinal direction, often narrow lines, leaving 

 broad, unmarked spaces between them, and not un frequently expand 



* "With shorter wings than mexicaiia, but with longer hill, like; cvinita ; throat and 

 over hreast light gray, not so dark as in crinita ; the black stripe along the inner webs 

 of the tail-feathers is broader, like stolida.^ [Type in Brit. Mus. J 



t "With short wings; all the wing-feathers, except the first, with rufous margins; 

 breast light ash-gray ; above lighter." [Type in Brit. Mus.] 



