MARINE WORMS. 241 



The place where this worm may be found is 

 easily known by a small heap of sand, somewhat 

 like a worm in shape, lying on the surface, within 

 eight or ten inches from which is. a circular de- 

 pression frequently rilled with water. The latter 

 is the place at which the lug protrudes its mouth, 

 and the former the point at which its tail is 

 extended to the surface, and between which two 

 points it can be obtained by digging to the depth 

 of eight or ten inches. 



On examining this annelid it will be found 

 that the upper extremity of the body is of consi- 

 derable thickness, and the lower end so much 

 thinner as to exhibit the appearance of a tail. 

 On opposite sides of the body rows of tufts of 

 a dark crimson colour will be found. These tufts 

 are the lungs or respiratory organs of the worm, 

 through which its blood circulates, and undergoing 

 the same process as the blood of fishes when pass- 

 ing through the gills, becomes suited to the pur- 

 poses of vitality. All the worms inhabiting the 

 sand form a tribe called Arenicolae. 



Another tribe of marine worms are those which 

 inhabit tubes, and are from this circumstance 

 called Tubicolse. The tubes they inhabit are 

 constructed by themselves, either from particles 

 of sand joined together by some species of cement 

 with which they are provided, or consisting of 

 lime secreted for the purpose by some process 

 similar to that by which the shells of various 

 crustaceans are formed. 



The Serpulae, of which there are several 



