birds and Pterosaurians, particularly Pterodactyles—and Prof. Newton has conclusively shown most interesting resemblances — Mr. Beddard considers the main difficulty "in the way of comparing Pterodacytles and birds is in the fact that both can fly, and that each has acquired the power of flight by a different method. Having acquired the power of flight, it seems clear that certain of the points of resemblance between them may easily be due to that mode of life, and may have been independently arrived at."
The consideration of the affinities brings us to the much-vexed question of the classification of birds, and "in considering a scheme of classification it is clear that we must bear in mind indications of the descent of birds"; and, in sketching the main outlines of a scheme, "attention must be paid only, or chiefly, to those characters which birds have inherited from their reptilian ancestors." But here a difficulty arises, if we seek the plane of low level in organization, by a plethora of undoubtedly reptilian characters. For "the few specially reptilian features in the organization of birds have, so to speak, been distributed with such exceeding fairness through the class that no type has any great advantage over its fellows."
Such discussions and conclusions as the above show the philosophical questions which may be debated and considered by the anatomical details of this volume, with its wealth of illustration. It would no doubt be possible to criticize; faultfinding is a facile occupation, but to recognize the great merits of a book is a more instructive process, even for a reviewer, than the eager quest for an error. We hold with Prof. Nichol on a literary subject—and the same remark applies to science — some "criticism has for its aim to show off the critic; good criticism interprets the author." This book is a standard contribution to ornithology.
This is a new edition, "almost completely" rewritten, of Wells's 'Text-Book of Biology,' published some five years back.
