1880.] Notice of some Aquatic Worms of the Family Naides. 423 
less, ranging from forty-two to forty-eight. Head ovoid, with 
the upper lip conical and more or less angular and obtuse. Eye- 
less. Caudal ring expanding into a broad, membranous, funnel- 
like pavilion, opening in a slanting manner dorsally and support- 
ing eight divergent rays (see Fig. 1); anterior pair of rays papil- 
liform; the others digitiform 
and successively increasing in 
length to the last pair. The 
rays are capable of extension 
beyond and retraction within 
the border of the pavilion, and 
this is also retractile, and when 
closed in the lateral view looks 
like the keeled prow of a boat. 
When the caudal pavilion is ex- 
panded, active ciliary motion is 
observed extending along the 
rays inwardly to the rectum, 
which motion most probably 
subserves a respiratory purpose. 
The anterior four rings of 
the body are provided on each Fic. 1.—Caudal pavilion, with the = 
side with fascicles of four or five ¢ nay wie beanie Us ok neal ae 
podal stylets, and the succeed- ra. 3.—Aulophorus vagus within a ie 
composed of Plumatella statoblasts, mag- 
ing rings with fascicles of three p ifie d about six diame Fic. 4.—Spade- 
or four stylets. The latter rings ike posi sie and be Fs s- 3de 
are also provided more dorsally Fie. 6.—Posterior extremity of the body of 
on each side with additional the 52™* with its three caudal appendages. 
fascicles mostly of a single stylet and a simple bristle. Stylets 
sigmoid with a median shoulder, and ending in a furcate hook 
(seé Fig. 2), 
Another of the little worms allied to the genus Dero, was col- 
lected together with some Plumatella scraped from a log in a 
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ditch of the meadows below Philadelphia. It was in the latter 
part of September, and the water collected contained a great many 
detached statoblasts or winter eggs of the Plumatella. The worm 
first attracted my notice from the fact that it occupied a tube com- 
posed of the Plumatella eggs cemented together, and which it 
dragged about in the same manner as the larva of the Caddis does 
its case (see Fig. 3). The only worm of European waters which 
5 
