“The author long ago won his spurs in this field, through his unrivaled researches in the phenomena of regeneration; and he has now proved himself a master of compilation—selecting the most significant experiments carried on in various countries, weighing them fairly, and summing up with a conservatism which is perhaps the most valuable feature of the book. The thoroughness and lucidity of the work make it serve three distinct purposes: the intelligent layman without any previous knowledge of the subject may read and appreciate any part of it; the student of experimental zoölogy will find it a veritable vade mecum; and the advanced scientist will be glad to refer to the generous summaries of literature relating to each subject.”—_Nation._ “Professor Morgan has, however, done much sound and some brilliant work. In his special field, the regrowth of amputated parts and the relation of this property to the general theory of evolution, his experiments have become classic, and he is himself one of the first authorities in the world. His own eminence in the field, combined with a simple, straightforward style, and a just and sympathetic appreciation of the work of other men, even when their opinions are opposed to his own, render him especially well fitted to sum up the general results of the new science. This he has accomplished with marked success in the work before us. He has succeeded in bringing together a large body of fact without becoming dull; without being fatuously ‘popular,’ he has been untechnical and clear.”—_Boston Transcript._ The Protozoa By GARY N. CALKINS, Ph.D., Instructor in Zoölogy, Columbia University _Cloth, 347 pp., 8vo, $3.00 net_ “The author has not aimed at putting forward an exhaustive, severely scientific treatise upon the group in question. His work may be described rather as a simple and intelligible introduction to the study of the Protozoa and of the many fascinating biological problems connected with, or illustrated by, this subdivision of the animal kingdom, in such a way as to awaken the interest of the beginner, no less than to strengthen the hands of the expert.”—_Nature._ Text-book of Palæontology By KARL A. VON ZITTEL, Professor of Geology and Palæontology in the University of Munich. Translated and edited by CHARLES R. EASTMAN, Ph.D., in charge of Vertebrate Palæontology in the Museum of Comparative Zoölogy at Harvard College, Cambridge, Mass. _Vol. I. Cloth, 670 pp., with 1476 woodcuts, 8vo, $7.50 net_ _Vol. II. Cloth, 283 pp., with 373 woodcuts, $3.00 net_