210 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



pigeon in the direction of the ring-dove. The differentiation does not meet on 

 the back of the neck as it does in the case of the ring-dove, but it extends farther 

 towards the middle of the back of the neck than does the iridescent area of the 

 passenger-pigeon. 



The tail of the hybrid is considerably longer than it is in tlie ring-dove, but falls 

 plainly short of the length attained in the passenger-pigeon. The general appear- 

 ance of the bird in size, color, and marking is intermediate. There are none of the 

 black spots of the passenger-pigeon shown distinctly in the hybrid, except in the 

 feathers on the posterior border of the wing. In the cage of living birds'" one could 

 probably identify the hybrid whose picture has just been shown, although the two 

 birds together there arc nearly of the same size. One can see the marking on the 

 neck of the one bird, and note that although it is slightly separated posteriorly it 

 comes near to a union on the back of the neck. A close examination of the hybrid 

 shows that there are some obscure marks on the scapulars, directly in the middle of 

 the back, and that there are also the faintest traces of some marks in the tertials. 

 Perhaps I have sufficiently described this hybrid; I think the bird exhibited here 

 is a fair intermediate between the two parent species. 



When I first began my experiments in hybridization I had much curiositj', 

 hardly knowing what to think would be the result of crossing two birds so different 

 as those just described. So far as the wild pigeons are concerned it was a wholly 

 unknown field at the time. I continued my effort, however, and got all the hybrids 

 I could — in the case of these two particular species I obtained 8 or 10 offspring. 

 These were all males and all of the same color. It was difficult to find any difference 

 between them. There was a slightly stronger trace of the sjiots in some cases than 

 in others, and a slight difference in the length of the tail. They never, however, 

 went much beyond the length seen in the individual exhibited here. 



* Some live birds were demonstrated in this lecture. — Editgu. 

 EXPL.^NATI0N OF PlATE 32. 



Fig. 1. Neck-mark of common pigeon X ring-dove h.ybrid. Totla del., Feb. 1903. X 1.1 



Fig. 1. Hows drawn so .as to show the extent of black and gray; sliarply cut feathers, and feathers less cut, p.issing 

 gradually into regular neck-feathers at each end of the rows and also above and below the rows. 



Figs. 2-6. Natural size. Show five feathers (left side) taken (Feb. 27, 1903) as follows: 



Fig. 2. Eighth feather of second row (counting from above downward). In this row we see 6 feathers shaded. 

 These feathers are not black, but gray with pale-gray tips. 



Fig. .3. Ninth feather of third row. Tliis from just below the feather shown in fig. 2. Here also 6 feathers shaded, 

 the 2 or 3 central ones becoming darker gray ; darker on posterior web. 



Fig. 4. Eighth feather of fourth row (fourth of 7 shaded feathers). From directly under that of fig. '.i. Black 

 or blackish gray; darkest on dorsal web. 



Fig. 5. Eighth feather of fifth row. Not quite so dark as that of fig. 4. 



Fig. 6. Seventh feather of sixth row. Slightly darker than fig. 2, but fighter than figs. :3, 4, or .'). 



Fig. 7. Hybrid between a male black Japanese pigeon (T 3 = common pigeon, with a touch of fantail) 

 and a female rinK-dove (St. risoriax St. nlhn, XW2D1). X 0.6. Toda del., Feb. 1903. 



Thishybriil il I \\,i> iKit.lnJ \iii;. 5, 1902. Head an. I ii. rk i.i slmw the neck-m.ark (neck held at normal length). 

 Three rows show lil:irl,i-li li:i-, - hihI nictallic-gray tips. .\Iim\c ihi-i iliree is one row in which blackish bases (dark 

 gray) show only ou liftiuf; tlic_' lYallurs; the tips are gray bcxuuiuig vinous iridescent at extreme tip. Then another 

 row with little differentiation. 



Below the three rows comes one which, in a little greater extension, shows black bases on 5 to 6 feathers, tips 

 gray, passing into vinous iridescence at extreme tips; then another row showing no black, but tips lustrous vinous; 

 only about 4 or 5 being cut shorter at tips. Tliu> llinc .iii' .ibnut 7 rows. 



All around the black and gray region, ulinli i oi iv.|miiic|- Im tlic ring-area in the ring-dove, there is vinous irides- 

 cence. No plain iridescence on front of ni .1,, .ind l.iil lilih- nn back of neck. 



The same neck-mark flat, and isolated feathers, shown in figs. 1-6. 



