62 



Lessons in Zoology. 



it is there for. To protect the eyes, of course. But the 

 legs and feelers, which are attached to the body by joints, 

 are all called appendages. These appendages are not all 

 in one piece like the bristles of the earthworm, but are 

 themselves jointed. For the first time we begin to study 

 animals with jointed appendages. 



We see that the abdomen 

 consists of six rings and a 

 flattened piece at the end 

 called the telson (Fig. 1, t). 



Fig. 1. 



tlG. 2. 



It is not to be wondeTed at if the tail £n pazzleg the class, with 

 the two broad lobes on each side of the telson, while in the cray- 

 fish the telson itself is jointed. Bnt after carefnl observation they 

 will see that the telson is a part of the body, while the lobes on 

 either side (Fig. 1, svfi) are parts of organs that are jointed to the 

 body, that is, parts of appendages. If this is clearly seen, the 

 next qnestion will be correctly answered. 



How many appendages can we find on any ring of the 

 abdomen ? 



There are two on each one. There is a pair of ap- 

 pendages on each of the six rings, but none on the telson. 



Are these appendages all alike ? 



