The Clam. 



45 



Fig 5, 



ward end of the shell, we lay the mantle back, as repre- 

 sented in Figure 5. Just under the mantle lie two of the 

 gills (Fig. 5, a), two delicate, fluted ruffles, and on the 

 opposite side of the body are two more. At the forward 

 end of the body are two pairs of delicate flaps, the palpi 



(Fig. 5, p), and be- 

 tween these is the 

 mouth (m). The 

 foot (/) is a curious 

 little lump of mus- 

 cle, easily found, 

 because there is but 

 one. Now we see how the clam can burrow in the mud, 

 and why he needs such a long siphon to reach up to the 

 water, while he is snugly hidden in his hole. 



So mnch the yonngest children can aee from the teaoher'a apeo- 

 imen. They should now draw the inside o{ one valve, and mark 

 on it the poaition of the gilla, the aiphon, the foot, and the mouth, 

 aa veil aa the impresaiona on the ahell. If there ia time, older chil- 

 dren, each with a clam in a small dish of water, can go further. 



A probe passed into the lower opening of the aiphon, enters the 

 bod; oavit; just below the gills. Water coming in at thia tube is 

 strained by the waving hairs on the gills, then passes through the 

 gills, giving np its oxygen to the blood on the way, and out by the 

 upper tnbe of the aiphon. At the same time by the motion of the 

 hairs, or cilia, tiny plants aod animala in the water are gathered 

 into threada and awept down to a chsonel on the lower edge of the 

 gilla, along which they move forward to the mouth. By lifting 

 the palpi a probe can be passed into the mouth. 



To aee the heart, out away the mantle from the top of the gilla, 

 being very careful not to cut anything else. In a little cavity jnat 

 behind the beak Ilea the heart, with the dark tube of the intestine 

 passing through the ventricle. The somewhat fan-shaped auricles, 

 one on each side of the ventricle, are not easily found except by one 

 skilled in dissection. 



To he seen distinctly, all these fleshy parts must he floated out 

 under water. 



