252 



use of thick and thin type, a reference to either figures or text 

 can be obtained at a glance. 



The illustrations throughout do the highest credit to the 

 artist, and, except where copied from figures in other works, 

 leave little to be desired as to correctness of detail or skilful 

 execution. In some few instances, however, as in the case of 

 Aleurodes on p. 591 (after Heeger), where the special charac- 

 teristic, called by Maskell the vasiform orifice, is omitted to be 

 shown, the authority copied from is primarily to blame. 



As a work of ready reference these volumes will doubtlf ss be 

 of great value to students and workers in this branch of Natural 

 History, whilst those desiring a fuller acquaintance with any 

 particular group will find foot-notes referring them to the best 

 authorities. The ordinary reader will, however, find much here 

 to interest and instruct ; and after noting that the known species 

 of Coleoptera are said to number 150,000, and those of the 

 Lepidoptera 50,000, he will probably lay down the book with a 

 feeling of wonder — not that the work has been so long in hand, 

 but that it has been possible from so wide a field of research to 

 collect and to compress so much information in so short a time. 



Dr. Sharp has not only given us a remarkably clear resume 

 of what is known as to the life- history and habits of insects, but 

 he has never hesitated to point out where our knowledge is at 

 fault, indicating thereby in numerous instances directions in 

 which there are still lines of enquiry waiting to be followed up. 

 He is greatly to be congratulated upon the successful issue to 

 which he has brought his section of this great work. 



Journ. Qmkett Microscopical Club, Vol. VII., No. 45, Nov. 1899. 



