ANNELIDS. 



435 



D 



as three hundred to four hundred segments, and may measure as much as 2 feet in 

 length ; the parapodia are flattened and leaf-like. During the day these animals 

 lie quietly in their 

 hiding - places, but 

 come forth at twilight 

 to swim about in 

 search of prey, when 

 the whole body, sup- 

 ported and in part 

 propelled by the 

 parapodia, executes 

 the most graceful 

 wave -like move- 

 ments. C shows a 

 species of the genus 

 Glycera, a compara- 

 tively dull coloured 

 form, which habitu- 

 ally lies hidden in 

 sand. These worms 

 make their burrows 

 by means of their 

 relatively colossal 

 proboscis, which is 

 studded with numer- 

 ous little warts and 

 teeth. From the 

 genus Glycera there 

 is naturally a passage 

 to the sedentary 

 group (Tubicola) of 

 polychsetous annelids, 

 and we may take as 

 our first example the 

 sand -worm (Areni- 

 cola piscatorum), re- 

 presented of the 

 natural size in D 

 of the illustration. 

 This worm reaches a 

 length of about 8 

 inches. Individuals 

 vary, however, much 

 in colour, according 



to the nature of the 

 mud or sand in which 



VAEIOUS ANNELIDS. 



A, Heteronereis stage of Nereis ; B, Phyllodoce laminosa ; C, Glycera ; D, Saiid- 

 worm or lug-worm, Arenicola piscatorum. (All nat. size.) 



