XENOPHON, on the colours of hunting dogs, 20.
XIMENES, Cardinal, regulations for the selection of rams, 20.

“YAHU,” the name of the pigeon in Persia, 5.
YAKS, domestication of, 20;
    —selection of white-tailed, 20.
YAM, development of axillary bulbs in the, 18.
YARRELL, Mr., deficiency of teeth in hairless dogs, 1, 25;
    —on ducks, 8, 22;
    —characters of domestic goose, resembling those of Anser albifrons, 8;
    —whiteness of ganders, 8;
    —variations in gold-fish, 8 (2);
    —assumption of male plumage by the hen-pheasant, 13;
    —effect of castration upon the cock, 13 (2);
    —breeding of the skylark in captivity, 18;
    —plumage of the male linnet in confinement, 18;
    —on the dingo, 22.
YELLOW fever, in Mexico, 23.
YEW, fastigiate, 21.
YEW, Irish, hardy in New York, 24.
YEW, weeping, 10;
    —propagation of, by seed, 12.
YOLK, variations of, in the eggs of ducks, 8.
YOUATT, Mr., history of the dog, 1;
    —variations of the pulse in breeds of dogs, 1;
    —liability to disease in dogs, 1, 21;
    —inheritance of goitre in dogs, 12;
    —on the greyhound, 1 (2);
    —on King Charles’ spaniels, 1;
    —on the setter, 1;
    —on breeds of horses, 2;
    —variation in the number of ribs in the horse, 2;
    —inheritance of diseases in the horse, 12 (2);
    —introduction of Eastern blood into English horses, 20 (2);
    —on white Welsh cattle, 3, 20;
    —improvement of British breeds of cattle, 3;
    —rudiments of horns in young hornless cattle, 13, 24;
    —on crossed cattle, 16, 17;
    —on Bakewell’s long-horned cattle, 17;
    —selection of qualities in cattle, 20;
    —degeneration of cattle by neglect, 21;
    —on the skull in hornless cattle, 25;
    —disease of white parts of cattle, 25;
    —displacement of long-horned by short-horned cattle, 28;
    —on Angola sheep, 3;
    —on the fleece of sheep, 3;
    —correlation of horns and fleece in sheep, 3;
    —adaptation of breeds of sheep to climate and pasture, 3;
    —horns of Wallachian sheep, 3;
    —exotic sheep in the Zoological Gardens, 3, 24;
    —occurrence of horns in hornless breeds of sheep, 13;
    —on the colour of sheep, 13;
    —on interbreeding sheep, 17;
    —on Merino rams in Germany, 20;
    —effect of unconscious selection on sheep, 20;
    —reversion of Leicester sheep on the Lammermuir Hills, 21;
    —on many-horned sheep, 25;
    —reduction of bone in sheep, 21;
    —persistency of character in breeds of animals in mountainous countries, 14;
    —on interbreeding, 17;
    —on the power of selection, 20 (2);
    —slowness of production of breeds, 21;
    —passages in the Bible relating to the breeding of animals, 20.
YOUNG, J., on the Belgian rabbit, 4.
YULE, Capt., on a Burmese hairy family, 14, 25.

ZAMBESI, striped young pigs on the, 3.
ZAMBOS, character of the, 13.
ZARCO, J. G., introduction of rabbits into Porto Santo by, 4.
Zea altissima, 9;
    —mays, 9.
ZEBU, 3;
    —domestication of the, 3;
    —fertile crossing of, with European cattle, 3, 16.
ZEBRA, hybrids of, with the ass and mare, 13.
Zephyranthes candida, 18.
Zinnia, cultivation of, 22.
ZOLLINGER on Malayan penguin ducks, 8.
ZOOSPORE, division of, in Algæ, 23.
“ZOPF-TAUBE,” 5.