164 



ORTHOGENETIC EVOLUTION IN PIGEONS. 



white mesial guinea-mark is the means by which the gray (blue) color of the wing is 

 extended. In the rock-pigeons and their closest allies the ruddy or chestnut suffu- 

 sion of the plumage is absent, and the naked periorbital region is quite small. Now, 

 in a guinea-pigeon mutation which occurred during 1909, all of these characters 

 are affected, and the variation is toward the rock-pigeon type in them all. 7 This 

 mutant demonstrates perfectly the community of patterns in the guinea-pigeons 

 and the rock-pigeons. 



The extent of these variations 8 from the normal C. guinea type is shown in the 

 illustrations. The second plumage of the mutant and its nest-mate are shown in 

 colored photographs in plates 76 and 77; the first plumage of the same two birds 

 is shown in an untouched photograph in plate 78. The guinea-mark and the naked 

 periorbital region of normal and mutant C. guinea are compared with the same 

 characters in other Columba in plates 79 and 80. The mutant's modification of 

 the light tail-band into a weaker band, placed in the middle of the black band of 

 the normal, is shown in plate 81. 



The editor has prepared tables 4 and 5, which give the available necessary data 

 for the origin and the breeding record of the guinea mutant. 9 That the mutational 

 characters were transmitted by the mutant is indicated by the data of table 5. 

 One (MN 1) of the two offspring (pi. 82) which lived long enough to permit a definite 

 decision on the point proved to be essentially like its mutant father; and the other 

 young, its clutch-mate, which died at the age of 14 days, was also believed to show 

 the mutational characters of the father. Indeed the descriptions of the two birds 

 when 2 weeks old (see below) would indicate that the short-lived bird (whose muta- 



Table 4. — The parentage and co-fraternity of the Guinea " mutant" No. 20. 

 C? C. guinea from dealer April 1908; typical. 



Jl. June 24f21,o\ typical; dead Dec. 20, 1909. 



J2. June 26\22, other; typical; alive Feb. 7, 1911. 



Kl. Sept. 24 23, ? ; typical; dead Dec. 12, 1909. 



K2. Sept. 2G 24, 9; typical; dead Nov. 24, 1909. 



LI. Jan. 30, 1910 weak shell; broken. 



L2. Feb. 1, 1910 weak shell; broken. 



Ml. Feb. 24(25, cf; typical; dead Jan. 19, 1913. 



M2. Feb. 26\other not hatched (care?). 



Nl. 



.0; dead at 12 days. 

 .0; killed day of hatching. 

 . 26 ; 9 ; typical ; dead July 9, 1912. 

 . no development. 

 .0; dead (killed?) at few days. 

 .0; dead at 10 days. 

 .27; typical; dead Jan. 6, 1916. 

 .28; typical; alive Nov. 20, 1910. 

 Certainly no other eggs before Dec. 1, 1910; later records 

 not kept. — Ed. 



Apr. 12.. 

 N2. Apr. 14 



01. May 11. 



02. May 13. 

 PI. June 30 

 P2. July 2 

 Ql. Aug. 24 

 Q2. Aug. 26 



'No reference is made to the changed character of the "bristling" bifid nock-feathers of the mutant, but the 

 illustrations here reproduced and all of the photographs made of this bird show much less of the "bristling" effect 

 in the mutant. In this character also, therefore, the mutant approaches the rock-pigeon type. — Ed. 



8 An additional variation — in the "dark spot" of the iris — in the guinea mutant is figured in plate 80, and 

 described in the accompanying legend. In this character, too, the mutation approaches the conditions now present 

 in Columba lima. — Ed. 



9 Though the parents were obtained from a dealer, probably no one who has worked with this species would 

 doubt that the author, who had long had this species under observation, would have quickly detected any impurity 

 or hybridism in the birds which were thus obtained and used as parents. This possibility is still further minimized 

 by the difficulty of getting hybrids of this species. (Chapter VIII ; see Vol. II.) 



10 Brackets indicate that the first and second eggs of the clutch wore not properly identified. 



11 The third (right) primary has two white spots near the tip — one on each side; this is :i case of abnormal albinism. 

 1S Note that the following clutch is succeeded bv a period of "rest." — Ed. 



