180 CRUSTACEANS 



and we are all familiar with the irresistible attraction 

 which bright light has for insects. But in a swarm of 

 billions of trillions of minute crustaceans it baffles 

 imagination to conceive of individual preference. 



Equally obscure is the purpose of the plume-like 

 decoration of many species of these living atoms, 

 which for extravagance and complexity of design can 

 scarcely be matched even in the headgear of feminine 

 humanity. 



Although some copepods are parasitic upon fishes 

 (salmon anglers are familiar with some of them), the 

 majority are free living, some being vegetarian, others 

 either scavengers or actively predaceous. Arctic 

 naturalists, we are told, are wont to turn the services of 

 another order of pelagic crustaceans Amphipoda to 

 serviceable account. When it is desired to obtain the 

 skeleton of a bear or seal, all that needs to be done is 

 to hang the entire carcase over the side of the vessel, 

 leaving it immersed for a few days, when the bones will 

 be found to have been picked perfectly clean by myriads 

 of little amphipods. The so-called fresh-water shrimp 

 (Gammarus pulex), beloved of trout, and the sand- 

 hopper (Talitrus and Talorchestia) belong to the order 

 Amphipoda. 



It is impossible for any one who is not a specialist in 

 that branch of research to which Professor Weldon and 

 Mr. Geoffrey Smith admit us to some insight, to rid 

 himself of a sense of wonder. It is absolutely 

 true, of course, that one natural phenomenon is not 

 really more marvellous than another. Sunrise and 

 sunset, a snowdrop pushing through the cold earth in 



