ANNELIDS. 
435 
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 
places, but 
hiding 
come forth at twilight 
about in 
prey, when 
to swim 
search of 
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 
polychaetous 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 
VARIOUS ANNELIDS. 
A, Ileteronereis stage of Nereis ; B, Pliyllodoce laminosa ; C, Glycera ; D, Sand- 
worm or lug-worm, Arenicola piscatorum. (All nat. size.) 
