48 THE CANADIAN ENTOMOLOGIST 



the subject is presented to us in logical fashion by a recognized authority. The 

 terminology of the wing-veins of insects has always been a subject for debate, 

 and the difificulties have not been diminished by the fact that at different times 

 various authors have adopted systems of nomenclature that have taken little 

 recognition of the work of others. Some authors, indeed, have not helped to 

 unravel the skein by using different systems even when dealing with the same 

 order of insects. It is a matter for congratulation, therefore, that Professor 

 Comstock has found it possible to gather together and present in book form 

 his numerous researches and those of other workers with a view to the adoption 

 of a uniform terminology, the well-known Comstock-Needham system. 



Commencing with what he considers as the most likely hypothetical type 

 of wing-venation, the author traces out the homologies of the wing-veins and 

 shows how the more specialized forms have arisen from the more generalized 

 along three quite distinct lines; namely, 1. Increase in the number of wing- 

 veins by the addition of accessory veins. 2. Increase in the number of wing- 

 veins by the addition of intercalary veins. 3. Reduction in the number of 

 wing-veins by the coalescence of veins, and also in many cases, by the atrophy 

 of veins. In support of his theories Professor Comstock brings to bear informa- 

 tion and facts laboriously gathered from the various provinces of palaeontology, 

 morphology, embryology and histology. In the first of these, judicious use is 

 made of the careful work of Anton Handlirsch embodied in his "Die Fossilen 

 Insekten und die Phylogenie der Rezenten Formen." Whilst on the whole 

 Professor Comstock agrees with the views of the palaeontologist, he differs with 

 Handlirsch in his idea that all insects had a common ancestry in the Pala'odicty- 

 optera of Devonian times. 



In a work that bears throughout the impress of the master-hand, it were 

 invidious to make distinctions; but we must say that the chapter dealing with 

 '■'The Basal Connections of the Tracheae of the Wings of Insects," written by 

 one of Professor Comstock's students, appeals to us particularly as a very careful 

 piece of work. It is shown that there is a strict correlation between the trachea- 

 tion of the wings of insects and the venation, although this fact is often obscured 

 in the adult to accord with its needs and habits. In the study of the tracheation 

 of the wings of nymphs and of pupa the truth of the conclusion is demonstrated 

 that the wings of all orders of insects are modifications of a single primitive 

 type, and that consequently it is possible to homologise the wing-veins of any 

 of the orders with those of any other order. 



In a series of nineteen chapters Professor Comstock discusses in detail 

 numerous types of venation as found in the various orders of insects, and a 

 valuable chapter outlining laboratory work in the study of the venation of the 

 wings of insects, enhances the value of the book as an aid to the teaching of the 

 subject in universities and colleges. The student will also find an exhaustive 

 bibliography of the more important works referred to in the text. The illustra- 

 tions are excellent, and the explanatory letters very distinct. 



Entomological Branch, Dept. of Agri., Ottawa, Ont. A. E. Cameron. 



Mailed February 28th, 1919- 



