1914] GrinncU : Manimnis nnd Birds of the Colorado Valley 159 



way, 1902. p. 210). The entire plumage in obscurus is very much 

 paler than in atcr. The former is drab throughout, slightly paler ven- 

 trally and very much paler, more clay color, on the throat ; the narrow 

 dusky shaft-streaks on the dorsum, chest and sides are clearly indicated. 

 The female of the eastern form is dark slaty hair brown with less 

 abruptly contrasted grayish throat. 



MEASUREMENTS! IN MILLIMETERS OF THIRTY-ONE MALES OF 



MOLOTHSUS ATER OBSCUBVS FROM THE LOWER 



COLORADO VALLEY 



No. 

 12960 

 12961 

 12962 

 12963 

 12964 

 1296.5 

 12966 

 12967 

 12968 

 12969 

 12970 

 12971 

 12972 

 12976 

 12979 

 12981 

 12986 

 12987 

 12988 

 12989 

 12990 

 12992 

 12993 

 12995 

 12998 

 13000 

 13001 

 1300.5 

 13006 

 13007 

 13008 

 Average 

 Maximum 

 Minimum 



Wing 



96.8 



97.8 



96.5 



102.3 



100.7 



1 no.4 



101.0 



103.3 



98.7 



97.3 



100.9 



101.4 



103.0 



100.0 



100.8 



98.5 



102.6 



103.7 



98.9 



96.7 



99.8 



103.1 



97.4 



101.3 



103.2 



99.4 



101.1 



102.5 



102.0 



99.1 



97.0 



100.2 



103.7 



96.5 



Mid-point of Range 100.1 



Variation on either! „ ^„ 

 f 3.6% 

 side or mid-point j 



Tail 

 65.3 

 64.7 

 63.8 

 68.3 

 69.6 

 66.4 

 67.5 

 66.7 

 64.5 

 65.0 

 66.4 

 66.0 

 69.6 

 67.4 

 65.5 

 69.3 

 69.9 

 68.5 

 64.7 

 66.2 

 67.0 

 70.5 

 66.2 

 70.0 

 69.4 

 64.6 

 67.0 

 70.0 

 69.7 

 63.6 

 07.0 

 67.1 

 70.5 

 63.6 

 67.0 



7.4% 



4.8% 



10% 



See text, pp. 157-158. 



