MOLOTHRUS. 451 
the length of the wing of about 0:5 inch. In specimens admitted to belong to 
M. pecoris the length of the wing varies from 4°5 to 4:0 inches!®; in one of our 
Mexican examples of MV. obscurus it measures 3°9, in another 3°95, and in the average 
of M. obscurus 3°75 inches 1°. Thus the dimensions, so far as regards the length of the 
wing, of /. pecoris and MW. obscurus appear to show a complete gradation between the 
two, and that there is no line of demarcation whereby they may be distinguished. 
The habits of J. pecoris, and how the hen bird lays its eggs in other birds’ nests, 
have been very fully described by various authors, Dr. Coues’s account being especially 
full of interest 12. Little has been recorded of this bird in Mexico beyond a note to the 
following effect by the late A. J. Grayson !*:—“ The birds whose nests are selected by 
M. pecoris in which to deposit its egg are usually smaller than itself. In the vicinity 
of Mazatlan the beautiful and basket-shaped nest of Vireosylvia flavo-viridis seems to 
be the one preferred. This Vireo is a summer visitant from the regions of Central 
America ; soon after its arrival in May and the early part of June nidification is com- 
menced. The nest is generally placed pendent between two branches usually low down. 
V. flavo-viridis is an abundant species on a small, thickly-wooded peninsula near the 
sea-shore, but a short distance from the city of Mazatlan. Here the Cow-bird was seen 
stealthily seeking an opportunity to drop its egg in the nest of the Vireo. Sheat length 
finds an opportunity, in the absence of the owners of the nest, but not before one egg 
at least has been laid does she deposit hers by its side, otherwise the Vireo would 
abandon it. The intruder’s egg is first hatched, and the others a little after. 
“ The larger size and the greater strength of the foundling absorbs all the attention 
of the poor dupe of a dame, and she proves a very affectionate and assiduous nurse to 
the stranger. 
“The Cow-bird is very numerous in the region of Mazatlan and Tepic, and is, in fact, 
pretty generally distributed over Mexico. About Mazatlan they are seen in large flocks, 
often in company with the larger M/. eneus.” 
The eggs are white, thickly covered with fine spots of ashy and purplish brown; 
others are blotched with large spots of purple and vinous brown. 
2. Molothrus sxneus. 
Psarocolius eneus, Wag). Isis, 1829, p. 758°. 
Agelaius eneus, Cass. Pr. Ac. Phil. 1848, p. 90’. 
Molothrus eneus, Scl. P. ZS. 1856, p. 300°; 1859, pp. 365*, 381°; Ibis, 1884, p. 4°; Cat. B. 
Brit. Mus. xi. p. 884"; Scl. & Salv. Ibis, 1860, p. 34°; R. Owen, Ibis, 1861, p. 61°; Cab. 
J. f. Orn. 1861, p. 81"; Cass. Pr. Ac. Phil. 1866, p. 18"; Lawr. Ann. Lye. N. Y. ix. 
p- 104"; Bull. U.S. Nat. Mus. no. 4, p. 247°; Mem. Bost. Soc. N. H. ii. p. 281"; Sumi- 
chrast, Mem. Bost. Soc. N. H.i. p. 552”; Frantz. J. f. Orn. 1869, p. 8303'°; Salv. P. Z. S. 
1870, p. 191°"; Cat. Strickl. Coll. p. 265°; Merrill, Bull. Nutt. Orn. Club, ii. p. 85”; 
Nutting, Pr. U.S. Nat. Mus. v. p.392”; Boucard, P. Z. 8S. 1883, p. 445”; Perez, Pr. U.S 
Nat. Mus. 1886, p. 151”. | 
o7* 
