170 NEW WORKS ON ENTOMOLOGY. 



gladly devote more space than I can here spare to a review of this 

 little book, so perfectly does it corroborate every "word which I have 

 said already as to the moral and intellectual value of such studies." 



INSECTA BRITANNICA-DIPTERA. Vol. III. 

 By Francis Walker, F. L. S. 8vo. pp. 352. With 10 

 plates. Cloth. Price 25s. London : Lovell Reeve 

 and Co. 



This volume, the concluding volume on the Diptera, as ori- 

 ginally intended (though we now hear there is some talk of another 

 supplementary volume), comprises the Nemocera and the Suc- 

 toridea, or Fleas, which are considered by Mr. Walker as 

 belonging to the order Diptera. 



The Nemocera he divides into ten families, viz. — 1. Myceto- 

 philidce. 2. Cecidomyidcc. 3. Bibionidce. 4. Simididce. 5. 

 Chironomidce. 6. Cidicidce. 7. Phlebotomidce. 8. Heteroclitce. 

 9. Tipulidce and 10. Bhyphidce. 



It must be very gratifying to Mr. Walker to hear the dictum 

 of the great Dipterist of Posen, Professor Loew, that the arrange- 

 ment " adopted by Mr. Walker is one of the best, or even the 

 best, systematic arrangement of the Diptera that has yet been 

 proposed." 



In the precise definition of species Mr. Walker has not been so 

 happy, and here there is much to be desired ; but considering how 

 vast is the subject, and how little encouragement the Dipterist 

 receives, we ought not to feel surprised at the frequent absence 

 of that almost mathematical precision which the describers of 

 Coleoptera and Lepidoptera have now attained. 



They have the advantage of having the differential characters 

 of species pointed out by some twenty or thirty pair of discerning 

 eyes, for many Entomologists who never wrote a book, nor even a 

 scientific paper, are most serviceable to the scribbling generation by 

 calling their attention to the differences, minute yet constant, which 

 tend to show the specific distinctions of certain insects. The 

 Dipterist has not this advantage, he works almost alone. Is it 

 surprising he should occasionally stumble ? 



Professor Loew (in the Review already alluded to, Nat. Hist. 

 Review, p. 92) remarks, " This work appears to fall very short 

 of what a Fauna of Britain ought to contain. The species already 

 known as British are not fully enumerated (in the second volume 

 especially), neither are the species given, all unquestionably in- 

 digenous ; on the contrary, many are introduced on mere con- 

 jecture and probability, as a considerable proportion of the species 



