THE LARVA 



claspers, one pair on each of the tenth and last segments, so that 

 there is a distance equal to the combined length of six segments 

 between the hindermost true leg and the first pair of claspers. But 

 even among the Geometers there are variations to be observed in 

 the number of claspers, and some of these will be pointed out in our 

 brief descriptions of the commoner species. 



These limbs which we have been calling claspers are known by 

 several other names. Thus they are termed ' pro-legs,' ' tempo- 

 rary legs,' ' false legs,' and ' abdominal legs ; ' but if you watch a 

 caterpillar as it walks up a stalk or along the edge of a leaf, 

 you will certainly agree that the term ' clasper ' is everything that 

 could be desired. But why not call them legs, seeing that they 

 are used in walking ? The reason is that they differ in many 

 respects from the three foremost pairs of 

 limbs as regards structure, persistency, and 

 function. The true legs, as we have called 



FIG. 24. -CATERPILLAR OP 

 THE IBON PROMINENT 

 MOTH (Dromedarius). 



FIG. 25. LARVA OF THE BRIMSTONE 

 MOTH (Luteolatd). 



them, continue to exist, though concealed, in the chrysalis state, 

 and again appear, far more perfectly developed, in the butter- 

 fly or moth, but the claspers are no more to be seen after the 

 caterpillar has passed into the quiescent stage. We have noticed, 

 too, that the true legs are pointed and clawed, also that they are pro- 

 tected by a hard and horny covering ; but examine a large cater- 

 pillar, holding it between the fingers and thumb with its under side 

 uppermost, and you will soon see that the claspers are not at all hard, 

 but soft and fleshy ; not pointed, but often terminating in a broad 

 flat circular surface. You will also observe, as the creature struggles 

 to escape from your grasp, and tries to get a hold on something with 

 its claspers, that these limbs, if we may so call them, are retrac- 

 tile, and are sometimes completely drawn into the body. Finally, 

 examine the broad end of a clasper with a magnifier, and you will 



