CHAPTER VII. 



CROSSES OF JAPANESE TURTLE DOVES WITH BLOND AND WHITE 



RING DOVES. 1 



The considerable number of tables presented here will serve in general for refer- 

 ence in connection with the condensed account of fertility and sex as given in 

 Chapter II. More particularly, they offer: (1) an opportunity to compare crosses 

 which are intermediate to the "distantly related and the closely related" forms 

 of Chapter IV; (2) they show again the effects of season and overwork on fertility, 

 longevity and sex; and (3) they present the following additional features not 

 hitherto considered: 



(A) The good effects of crossing related genera as seen in (a) the long term of life of 

 the offspring; (&) the development of all, or nearly all, of the eggs; (c) the predominance 

 of males from the eggs of the spring and early summer and from "uncrowded clutches" 

 generally. 



(B) It will be seen (a) that the two eggs of the clutch of the pure females have different 

 sex tendencies, and (6) that there is some evidence that unpaired eggs (i. e., eggs from 

 clutches of one egg only) apparently have stronger sex tendency than have the paired eggs, 

 in that they are more independent of season and overwork, in their production of sex, 

 than are the paired eggs. 



(C) The fertility of hybrids from these related genera present the following situation : 

 (a) The hybrids crossed inter se or with their parent species are usually less fertile than 

 was the original cross, their young live less long, and the sex of the offspring is probably 

 less dependent upon season and overwork, and certainly bears little or no relation to the 

 order of the eggs in the clutch; (6) eggs from matings of complex hybrids are probably 

 more fertile than from matings of F : inter se, or from F, with the parent species; the term 

 of life is probably also longer than from that cross, though this term is shorter than that 

 for the Fi individuals themselves. 



(D) The further breeding of the F t hybrids and also of complex hybrids, produced a 

 high percentage of (a) abnormal young, and (6) of hermaphrodites. 



(E) The crosses of St. alba and of St. risoria with T. orientalis show that color is here 

 a sex-limited character. 



'The text of this chapter was written by the editor; nearly all of the tabulated data are those of the author. 



EXPLANATION OF PLATK 8. 



A. A<lult female white ring-dove, Streptopelia alba, x 0.5. Rowland del., Sept. 1914. 

 The ring has been over-emphasized in its depth of color. I'll). 



B. Adult female blond ring-dove, Streptopelia risoria. x 0.5. Hayashi del. 



View of entire bird. The three separate feathers are (from left to right) the extreme upper, middle, and lower 

 parts of the ring or neck-mark. The general color could be described as a pale fawn, or isabelline, which becomes 

 lighter on the throat, and fades out towards and around the vent, passing imperceptibly into the white of the under 

 tail-coverts. The black ring is sometimes narrower at its middle on the back of the neck than at the ends. This 

 fact, together with the complete interruption of the ring on the back of the neck in the first plumage (by which it is 

 broken into two portions, one on each side of the neck, beginning a little below and behind the ear-coverts and growing 

 narrower backward), auggeeta that the half-ring has arisen by the extension of two spots like those seen in the mourning- 

 ilove. This ring is creamy-white in the "Vienna white dove" (.S7. iillxi). It is often reduced to a mere sluidow, or 

 wholly absent, in the first plumage. 



68 



