MUSEUM OF COMPARATIVE ZOOLOGY. 225 



the Pacific coast, and figure 17 with the so-called Passerculus alaudi- 

 nus* also of the Pacific coast. 



Plate VI, although designed more especially to illustrate local varia- 

 tion, indicates to some extent the individual variation existing in Age- 

 Iceus phoenkeus. Figures 1 and la represent the average type of the 

 hill in this species in Massachusetts, and figures 3 and 3a, and 4 and 

 4a, unusually long and unusually short forms of the bill found at the 

 same locality. Figures 2 and 2a, 5 and 5a, and 6 and Ga, represent a 

 similar series from the St. John's River, Florida. All the specimens of 

 the two series are adult males. 



Plate VII represents similar variations of the bill in Quiscahi* 

 purpureus. Figures 1 and la, 3 and 3a, 4 and 4a, and G andfGa, 

 represent the average and the extreme types of the bill met with in 

 Massachusetts males. The latter also represents an inflexed type of 

 bill, a modification seen in many species, it being especially common in 

 the Quiscali and other genera having the bill of a similar form. It is 

 unmistakably an individual peculiarity, evidently depending mainly 

 upon age, and resulting from the upper mandible outgrowing and over- 

 hanging the lower. In Quiscalus purpureus such specimens are more 

 or less frequent at probably all localities, they having been received at 

 the Museum from Maine, Massachusetts, New Jersey, Florida, and 

 Illinois, and I have seen them from the "West Indies. It often gives 

 rise to the name inflexirostris, which is found so frequently a synonyme.f 

 The figures of the bills of four females of Sturnella ludoviciana (Plate 

 VIII), from Florida, indicate the character of the bill variation ex- 

 hibited by different individuals of this species at the same locality, 

 independently of any variation attributable to sex. Figures o and oa, 

 and G and Go (same plate) show that like variations occur in Colaptes 

 auratus, the figures being drawn from two Massachusetts females. 



Similar comparisons, with similar results, might be made with scores 

 of other species, but the above illustrations will doubtless suffice to show 

 that individual variation in the form of the bill is not only great, but 

 that it exists in groups having a high grade of structure. Other groups 

 might have been chosen in which the individual variation in the form 

 of the bill, as already stated, is far greater than in the instances above 



* Bonaparte, Comptes Rendu?, Vol. XXXVII, p. 918, 1853. 



t Concerning Quiscalus i/ijltxirostris Swuiuson, see below (Part IV), under Q. pur- 

 pureus. 



VOL. II. 15 



