126 



BOYS AND GIRLS IN BIOLOGY. 



from it, one can hardly count them all, much less learn 

 them. Counting from behind forward, you will find 

 between the lobster's body, or abdomen, and the head, 

 eight pair of jointed legs or arms, or both, one pair 

 much longer and larger than the others, with huge pin- 

 cers (Figs. 109, 116) at the ends. All these eight pair 

 are called the thoracic appendages, because they are 

 fastened to the thorax, or breastplate. The lobster uses 

 the four back pairs for walking, and so they are called 

 the ambulatory limbs. Amble means to walk. The 

 last pair has seven joints, and every joint works in a 

 different direction, so when these hind-legs start off it 

 is hard to tell where they intend to go. The next pair 

 of walking-legs are like the hindmost pair, except that 

 the first joint sends out a piece above it which is kept 

 out of sight in a little room in the side of the lobster 

 (Fig. 116). We shall hear more about this little room 

 by-and-by. The two front pair of walking-legs send 

 up pieces also into this chamber, but the end of the leg 

 is different from the last two pairs, for they have pin- 

 cers, or chelae (Fig. 109). Now we have come to the 

 longest pair ; the chelae, or pincers, at the ends are so 

 large and strong, that they are called the great chelje 

 (Fig. 109). These are the pincers that the old fish- 

 woman fastened, and they are the lobster's weapons of 

 defense. He is a queer soldier, and has introduced 



