WORMS. 
44 ° 
although it is capable of stretching itself much further, and its width is about 
equal to that of a man’s finger. On account of their burrowing habits, worms 
are not very frequently seen, although periodically—but only after heavy rains— 
they come to the surface of the soil in some numbers. Allied to the earth-worms 
is the rare and extremely slender Phreoryctes menkeanus, which lives from 
preference in wells and shallow water, in which it may be found in the greatest 
abundance in May and June, disappearing in the winter. Another aquatic 
member of the group is Tubifex rivulorum, a small red, translucent little worm, 
found abundantly on the slimy bottoms of ditches and brooks. These creatures 
remain with the forepart of the body stuck in the slime, while the hinder end 
keeps up a continual vibrating movement. Usually they are so closely packed 
that the surface of the mud appears to be red coloured, and when startled, the 
whole throng disappears like a flash into the slime. The clear transparent naids 
behave in quite a different manner. These animals are also found in ponds 
and ditches, where they 
may be seen winding 
themselves in and out 
amongst the stems of 
duck-weed. One of the 
best known is the beaked 
nais (Nais proboscidea), 
so called from a feeler¬ 
like prolongation of the 
head, which is furnished 
with two conspicuous 
eyes. These worms 
frequently reproduce 
spontaneously by fission, 
and it is not uncommon 
to see one individual in 
process of giving rise 
to several others. 
Amongst the bristle- 
worms is placed the 
family Myzostomatidce, 
which was long a puzzle 
to zoologists. The species 
are all of small size, the largest, Myzostoma gigas, measuring only a little more 
than a quarter of an inch in length. The body is short and oval. Its upper 
side, which is variously coloured, is covered with fine threads, called cilia, and its 
edges are prolonged into ten pairs of long, slender, flexible appendages, while 
below there are five pairs of horny tipped parapodia, and four pairs of cup-like 
suckers. All the members of this anomalous family are parasitic upon stone- 
lilies or crinoids, but the degrees of parasitism are various, some kinds wandering 
freely about their hosts, while others cause those curious swellings which appear 
upon the arms of the infested animal. 
beaked NAIS, JYctisproboscidea (enlarged 10 times). 
