iqo3 The Field Naturalist's Library 347 



The rest of the volume deals in a similar manner with the insect- 

 eating mammals, carnivorous birds, insect-eating birds, carnivorous 

 and insectivorous reptiles, amphibians, and fishes, worms and molluscs, 

 carnivorous insects, spiders, crustaceans, starfish, sponges, and finally 

 the Protozoa. Then we are taken again to the highesl mammals whi< h 

 feed upon plants, and on e more tra< e the plant-feeding animals down 

 the scale through each class. Lastly, in the volume, the omnivorous 

 animals are dealt with in similar order. 



It will be seen that the scope of this volume is that of one of the 

 most interesting of the phases of animal life : and Professor Davis has 

 used the opportunity well. We note that the author includes birds and 

 small mammals in the dietary of the English grass snake (T. natrix), 

 in spite of the fact that some very high authorities would restrict its 

 diet to amphibians and fish. In this Professor Davis has our support, 

 though we should like to know his evidence. We have recorded the 

 finding of birds in the gullet of this species, and quite recently a mole 

 was similarly found. Nor could we ever understand the partiality 

 exhibited by this snake for tree-climbing, except on the supposition 

 that it was after small birds. The British adder is given the old 

 specific name of Pelias bents : it would have been better to use the 

 more accurate one of Vipera bents. 



Space forbids our following Professor Davis through this interesting 

 volume ; but the above resume of its contents will show our readers 

 that it will well repay perusal, and give the field naturalist just the kind 

 of information which he specially wants. 



Volume iv. concerns itself with another aspect of animal life, 

 namely, "Animal Defences," and here again we are of opinion that the 

 subject is dealt with admirably and freshly. The numerous protective 

 devices which enable animals to evade or escape from the attacks of 

 more powerful forms, constitute one of the most fascinating pages of 

 natural history, throwing light on the great principle of the survival 

 of the fittest and the corresponding elimination of the least fit. 

 Professor Davis well says that " it is impossible to avoid language 

 which seems to attribute conscious effort or knowledge on the part of 

 this or that animal ; but under a great many of the headings employed, 

 such as 'precautionary measures' and 'passive defence,' the defence is 

 of purely unconscious kind, and has been determined by evolutionary 

 factors, working irrespective of the will or knowledge of the animal." 

 The animal defences are classified under the heads of precautionary 

 measures, resistance, and retreat. Under the first head come bodily 

 characteristics, as far as they result in inconspicuousness or the contrary : 

 and, secondly, the mode of life, i.e. the feeding at favourable times and 

 in favourable places. Resistance takes the form of passive defence 

 by means of bodily characters, such as unpalatability, possession of 

 armour, special instincts (as death-feigning), or unusual fecundity. 

 Also, there is active defence by mean-, ol a] re ive weapons, defensive 

 weapons, and the use of the practice of co-operation. The use of 

 retreat involves the habits of animals in movements, burrowing, flight, 



