FRILLS AND FUNDAMENTAL BARS AS PLUMAGE CHARACTKKS. 



145 



I find that the maternal grandmother (Turtur orientalis) of these birds shows the 

 same crease to nearly the same extent. 



THE BREAST- CREASE AND FRILL IN OTHER HYBRIDS AND IN FERAL SPECIES. 



A hybrid (B 2), from a male mourning-dove and a female risoria X alba hybrid, 

 shows most of time, but not continuously, a short crease or dimple below the chin 



TEXT-FIGURE 26. 



A. Hybrid; mourning-dove x ring-dove (B2); hatched Aug. 1, 1898. x 1. Wilson del., March 17, 1900. Sire, 



Zenriidura carolinensis', dam, hyb. St. alba-risoria x risoria-alba. 



Most of the time, but not continuously, shows a short crease or dimple below the chin. The dimple tends to per- 

 sist , but the projection of one or two feathers is a purely transient phenomenon. It is not due to feathers being ruffrd 

 by external means, but to the position which they assume automatically and occasionally, showing that the condition 

 is such that a very slight variation such as arises spontaneously and disappears as readily expresses itself now in 

 projecting feathers, now in feathers lying more smoothly. 



B. Adult Geopelia striata. x 1. Wilson del., March 1900. Showing a full breast crease. This is transient and is some- 



times visible only in one or another part. 



C. Same fraternity with three-fourths hybrid of text-fig. 25; white (B2), hatched Aug. 24, 1899. Wilson del., March 



1900. This bird shows quite uniformly a crease of about the length indicated. I find that its paternal grand- 

 mother (Turtur oritntalis) shows the same crease to a similar extent. 



D. Juvenal Geopelia humeralis, just hatched, x 4. Hayashi del., Aug. 1904. The down feathers of the upper throat 



curve upward. If the later feathers should be similarly oriented they would form frills. 



(text-fig. 26, fig. A). To-day a single feather on each side is tipped edgewise so as to 

 project like frill-feathers, although not strongly. These feathers were noticeable for 

 most of the day, but later were smoothed out, leaving only the dimple. The dimple 



