124 



BOYS AND GIELS IN BIOLOGY. 



breast, or thorax, making the two pieces of shell winch 

 cover the head and breast all one. So the first and sec- 

 ond division of the body, thus joined in one, are called 

 the cephalo-thorax, or head breastplate. The large 

 piece of shell, with the seam that covers the back and 

 sides of the cephalo-thorax, is called the carapace, or 

 shield (Fig. 109). It is the front sharp point of the shield 

 (carapace) that is called the frontal spine, or beak. 

 Behind the head and breast — cephalo-thorax — lies the 

 third division of the body, the abdomen, which is made 

 up of seven pieces, or joints ; the first six joints are 

 called somites (Fig. 109), or bodies, and the last joint, or 

 tail-piece, is called a telson, which means end. So the 

 body of the lobster is made up of six body-pieces, or 

 somites, and a tail-piece, or telson. Each body-piece 

 has a pair of soft-jointed paddles on its under-side, and 

 these are called swimmerets, or little swimmers (Figs. 

 109, 116). The lower joints of these paddles have two 

 broad, flat toes. The paddles on the last, or sixth, so- 

 mite are different from the others ; they are wider, and 

 turned backward (Fig. 116), so as to lie at each side of 

 the tail (telson), and these great fringed paddles, taken 

 with the telson, form what is called the tail-fin, from 

 its likeness to the tail of a fish. The under or ventral 

 part of each somite, or body-piece, which lies between 

 the paddles, is called the sternum (Fig. 110). The 



