44 



ARKIV FÖR ZOOLOGI. BAND 13. NIO 4. 



Unfortunately Dr. Bovallius only collected a single 

 specimen of V. /. insulanus and I have no further examples 

 of F. /. flavoviridis for comparison. But of the descriptions 

 given by the authors referred to, I can only find, that the 

 San Miguel Vireo must be regarded as an insular race of the 

 mainland bird in like manner as F. /. forreri (Madarasz) of 

 the Tres Marias Islands. 



The same opinion was also expressed by Thayer and 

 Bångs (1. c). They say, «Still all these characters are average 

 ones, and had not Ridgway in Birds of North and Middle 

 America treated the bird as a distinct species, we should feel 

 inclined to reduce it to a subspecies of F. flavoviridis.» 



To show, why the race of San Miguel and that of Tres 

 Marias Islands must be given the same rank, I here give their 

 subspecific characters compared with those of F. /. flavoviridis. 



Back. 



Superciliary stripe 



Låter al line of pileum 

 Wing, average 

 Tail, average . 

 Culmen, average 

 Tarsus, average 

 Middle toe, average 



V. f. forreri 

 (Madaraz) 



Alike. 



Darker gray, less dis- 

 tinct, often obsolete. 



Dusky, less distinct, 

 often obsolete. 



Greater. + 4,9 in male. 

 Greater. + 4,1 in male. 

 Greater. + 0,5 in male. 

 Greater. + 1,2 in male. 

 Greater. + 0,4 in male. 



V. f. insulanus 



(Bångs) 



Duller. 



Paler, more distinct. 



Dusky, more prono- 



unced. 

 Smaller. — 1,9 in male; 



— 3,8 in female. 

 Smaller. — 0,6 in male; 



— 2,4 in female. 



Smaller. — 0,9 in male; 



— 0,5 in female. 

 Smaller. — 1,7 in male; 



— 1,2 in female. 



? + 0,8 in male; 



— 0,3 in female. 



This collation is arrived at according to the measure- 

 ments given by Ridgway (Op. cit.) and it must be remarked, 

 that of F. /. flavoviridis he measured 24 ^S, H ??; of F. /. 

 forreri 7 SS\ and of F. /. insulanus but 2 ^S, 2 $$. 



According to the above comparison, it is obvious enough, 

 that there is no reason for placing the form of Tres Marias 

 Islands as a subspecies and at the same time give the San 

 Miguel bird the rank of a species, as was done by Ridgway. 

 I prefer regarding them both only as insular races. 



In the present specimen the coloration as to Ridgway's 

 «Color Standards», 1912, is as follows: 



