WORMS. 



69 



features of its history. From the eggs there hatch out individuals which 

 have no sexual organs, and hence would not be able to perpetuate the 



species, were it not for the 

 fact that they divide in al- 

 most the same way that 

 does the Nais described on 

 a previous page, and these 

 worms thus budded off are 

 male and female. This 

 genus is also noticeable 

 from the fact that it be- 

 longs to a family in which 

 portions of the feet become 

 long and jointed, thus sim- 

 ulating the structure which 

 we shall find farther on 

 among; the Crustacea and 

 Insects. 



The tube-dwelling; worms 

 are modified to accord with 

 their habits. Living as they 



Fig. 65. -Scaly marine worm Offer le). ^ Q a sedentary life there is 



no necessity for well-developed feet, while the fact that 

 they live in a tube necessitates the existence of structures 

 to bring food within reach of the mouth and oxygen to 

 the blood. 



Among the least modified of these forms is the lob- 

 worm (Arenicola), which is abundant, buried in the sand 

 near low-water mark. It occurs on our coast north of 

 Cape Cod, as well as in Europe. It is really beautiful. 

 The body is a dark green, varied with a lighter yellowish 

 brown, and studded with black spots, while the bushy gills 

 shown in the figure are a beautiful dark red. With us this 

 worm is regarded as of no account, but in Europe it is dug 

 extensively, and used as a bait in fishing. Its burrows can 

 readily be recognized from the peculiarly shaped coils of 

 nd near them. 



On the rock-weed one finds abundantly little white 

 shells, coiled in a spiral much like that of a snail. These 

 are the tubes of a small worm known as Spirorbis, while 

 the dredge frequently brings up a very similar but larger form (Serpula) 



Fig. 6»>. — Lob-worm 

 (Arenicola) taken 

 from its burrow. 



