48 THE SCOTTISH NATURALIST 



what is known regarding every aspect of the subject which will be of 

 the greatest value to the entomologists, medical men, and health ofificers, 

 for whom it has primarily been written. The earlier chapters are devoted 

 to a detailed account of the structure, external and internal, of the mature 

 insect, and these are followed by an account of its habits and bionomics. 

 Then follows Part II., dealing with breeding habits and the structure and 

 life-history of the larva ; Part III., the natural enemies and parasites of 

 the fly; and Part IV., other species of flies frequenting houses. Parts 

 V. and VI. are important, the former dealing with the relation of House- 

 flies to disease, and the latter being devoted to the practical measures 

 necessary to cope with the rapid multiplication of the insect and its role 

 as germ-carrier. With the possession of this volume the reader may 

 justifiably feel that he has at hand all that it is necessary for him to learn 

 on the subject, but for the more ambitious worker a full bibliography, 

 comprising no less than 36 pages of titles, is provided. Considering the 

 amount of work involved in the preparation of this useful volume, the 

 price is an exceedingly moderate one. 



Textbook of Embryology (Edited by Walter Heape). Vol. I. 

 " Invertebrata." By E. W. MacBride. Macmillan & Co., London, 

 1914. pp. xxxii-f 692. Price 25s. net. 



Should the remaining volumes of this work reach the standard of 

 that before us, then, without hesitation, we would state that this is one of 

 the most useful Zoological textbooks ever published in this country. 

 Certainly there has appeared neither here nor elsewhere so concise, well- 

 illustrated, and comprehensive an account of the embryology of the 

 Invertebrates. Since space demanded selection, the author has chosen 

 his examples with reference to the thoroughness of the knowledge of their 

 life-histories and to the ease with which the forms could be obtained. 

 The result is a work which will enable the student to grasp with the 

 least possible expenditure of time and energy the bearing of the latest 

 researches on the early development and functioning of the lower 

 animals, and which will guide the researcher along the paths most likely 

 to yield fruitful results. Where so much is excellent it seems ungracious 

 to criticise, but we would suggest that it is misleading to say of a species 

 to be found under rock-ledges at low-water mark on most parts of the 

 coast of Britain, that "the British Tubidaria indivisa is found attached 

 to the bottoms of old boats" ; and that where so much attention is given 

 to special developments among, say, Echinoderms, it is unfortunate that 

 the unique and highly specialised free-swimming gonophore oi Dicoryne 

 conferta among Hydrozoa should pass unnoticed. The paper of 

 Koeppern's referred to the Proc. Roy. Soc. Edin. (p. 370) was published in 

 the Proc. Roy. Physical Soc. Edin. Professor MacBride is to be con- 

 gratulated on the appearance of this valuable volume, and especially 

 on the many beautiful original figures which illustrate his account of 

 Echinoderm development. — J. R. 



