40 The Microscope. 



when they have become mere rudiments, -^^ inch or less in length, 

 the articulations posterior to this point bearing rudimentary podal 

 stylets only. This an-angement of the bristles gives the worm an 

 attractive and unique appearance, when present in the beautiful 

 regularity often to be observed. Occasionally, especially in the 

 largest and presumably oldest worms, the symmetrical arrangement 

 is interrupted by the interposition of one or more extremely long- 

 bristles. 



The intestinal canal is capacious, brown in color, moderately tor- 

 tuous, and distinctly divided into pharynx, cesophagus and intestine. 

 The pharynx extends from the mouth to the beginning of the sixth 

 articulation. It is protrusible, the worm thrusting it out in order 

 to seize the vegetable particles and diatoms on which it feeds, and at 

 times using it as a sucker to assist in progression. The upper sur- 

 face of the passage is ciliated, and one characteristic feature, the one 

 that has suggested the specific name, is the lemon-yellow color which 

 tinges the whole organ, and extends to the beginning of the oesopha- 

 gus, where it abruptly ceases. It extends into the upper lip where 

 it is most distinct near the lateral margins. In both these parts thft 

 color often deepens to an orange hue. 



At the beginning of the sixth articulation the pharynx is con- 

 tracted and becomes the CBSophagus, which occupies only the sixth 

 and seventh segments. In the eighth the passage suddenly dilates 

 into a sub-cordiform or sub-spheroidal sac, the intestine again nar- 

 rowing in the ninth, while in the tenth and eleventh it again forms 

 an obovate enlargement, contracting near the beginning of the 

 eleventh, and thence continuing tortuously to the anal aperture. 

 The portion of the canal passing through the fifteen or sixteen pos- 

 terior articulations is ciliated. 



From the beginning of the CBsophagus at the sixth segment to 

 within five or six articulations of the posterior extremity, often as far 

 as the anal segment, the tubular passage is abundantly supplied with 

 small, golden-brown granules or refractive oil drops, probably repre- 

 senting an hepatic organ, or being cells having an hepatic func- 

 tion. They are densely aggregated over the intestine near each 

 membranous dissepiment, the tube appearing to be transversely 

 striated by very dark, narrow bands. 



Segmental organs, apparently ciliated, are present on each side 

 of most of the articulations. 



The worm measures from j\ to j\ inch in length; in gi'eatest 

 inch. It has been obtained in abundance on the lower 



