1880.] Notice of some Aquatic Worms of the Family Naides. 425 
from the back end. The worm moves in jerks, alternately 
extending the fore part of the body and projecting the podal fas- 
cicles forward and hooking into the surface on which it is creep- 
ing, and then contracting the fore part of the body and dragging 
along the back part enclosed within the tube. Frequently the 
motion is aided by the eversion of the pharynx, so as to forma 
disk or sucker which adheres to surfaces, like that of a leech. 
The movements occur in quick succession, so that the worm 
creeps about quite actively. At times the worm will double on 
itself and in this way pass through its tube and reverse its direction. 
At times too it will leave its tube and creep about without one. 
The papillz of the anal aperture are clothed with vibratile cils, 
which produce an active current inwardly as observed in Dero. 
Another little Naiad with conspicuous caudal appendages, in all 
other respects except in the possession of the latter, resembles 
Pristina, and I have therefore regarded it as such, with the name 
of Pristina flagellum. Its characters are as follow: Body com- 
pressed cylindroid, transparent, with red blood. In a specimen 
one-fourth of an inch long and exhibiting evidence of division 
into two individuals, there were about sixty rings, or thirty to 
each division. Head conical and prolonged into a digit-like upper 
lip (Fig. 5). Eyeless. Caudal ring furnished with three long 
digit-like, blunt appendages, trailing behind; the lateral pair nearly 
twice the length of the intermediate one (Fig. 6). Podal stylets 
in fascicles of four, on each side ventrally, to all the rings except 
the terminal ones; sigmoid with a median shoulder and ending 
in a furcate hook. Bristles to all the rings dorso-laterally, except 
the terminal ones, in fascicles of three to six. 
Length of worm, 6 to 7 mm.; breadth 0.3 mm.; length of 
digit-like upper lip from the mouth, 0.25 mm.; length of lateral 
caudal appendages, 0.75 mm.; of intermediate one, 0.375 mm. ; 
length of bristles, 0.25 to 0.375 mm. Creeping among aquatic 
plants in the ponds of sphagnous swamps, New Jersey and Penn- 
sylvania. 
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