420 



NORTH AMERICAN BIRDS. 



In regard to the parentage of the eggs thus discovered, the coloration and 

 size of which correspond so closely with those of the Poor-will, Mr. Salvin 

 writes, in a letter dated March 10, 1872 : " In respect to the Antrostomus 

 which lays white eggs in Guatemala, I have carefully examined the skin of 

 the female sent to me with the eggs in question, and represented as their 

 parent. It certainly is not A. nuUalli, but appears to belong to the spe- 

 cies described by Wagier as A. macromystax. This species is very closely 

 allied to A. vociferus, but appears to be sufficiently distinct, inasmuch as 

 the rictal bristles are very long, the throat is almost without white feathers, 

 and the white on the tail is more limited in extent than in A. vociferus. 

 The true A. vociferus is frequently found in winter in Guatemala, but is 

 probably only a migrant. The other species would certainly appear to be a 

 resident in South Mexico and Guatemala. With respect to A. nuttalli, I 

 may add that I have recently acquired a skin from Guanajuata, in Mexico. 

 This is the first instance of the occurrence of the species in Mexico at all, 

 that I am aware of." 



Mr. Eidgway met with the Poor-wiU from the eastern slope of the Sierra 

 Nevada to the Wahsatch and Uintah Mountains. He describes its notes as 

 much like those of the eastern A. vociferus, except that the first syllable is 

 left off, the call sounding like simply jpoor-ivill, the accent on the last sylla- 

 ble. It frequents chiefly the dry mesa and foot-hills of the mountains, and 

 lives almost entirely on the ground, where its two white unspotted eggs are 

 deposited beneath some small scraggy sage-bush, without any sign of a nest 

 whatever. Both sexes incubate. 



sternum of Chordeiles virginianus. 



Sternum of Caprhnulgus stictomus. 



