74 RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY, 



ing after the girdle, usually one, often two, upon each side of the 

 annuli. Head obtusely rounded and prolonged into a cylindroid, 

 v^ery movable, digitiform, transversely wrinkled proboscis. Caudal 

 annulus terminating in two short lobes. 



Length 3-4ths to i inch ; breadth i-5thto i-4th of a line. Length 

 of proboscis i-2oth inch. 



Remarks upon the Ilabits. — When at rest the worm lies with the 

 anterior four-fifths of the body upon the surface of the mud at the 

 bottom of the water, with the tail fifth buried. It is very active in 

 its movements. It also constructs tubes of mud. It is hermaphro- 

 dite, and copulates in the same manner as the earth worms. 



In a number of individuals I observed bunches of spermatozoa, 

 and in several of the same from three to five nearly completely formed 

 ova placed just posterior to the girdle. The eggs when extruded 

 were attached to the inside of the vessel in which the worms were 

 kept. They consisted of an oblong quadrilateral translucent, whitish, 

 papyraceous web, enclosing a light amber-colored, bottle-like case, 

 with an open neck, and the body containing white globular mass, 

 the true ^z%. 



The perfect worm after living about two months died. Some of 

 the ova several weeks after their extrusion were observed to have the 

 young almost perfected, and these a few days after their escape pre- 

 sented the following characters : 



Body cylindroid, divided into 35 annulations, each with a pair of 

 fasciculi of four or five hooks ; posterior to the first three also pro- 

 vided on each side with one or two setae. Tail bilobed. Head as in 

 the parent. No girdle ; no indication of division, and no apparent 

 developing annuli at the tail end. Length 2 lines. 



[November. 1853. No. 128. See Bibliography.] 



Dr. Leidy stated that the nodular bodies imbedded in the tails and 

 fins of the fishes presented by Dr. Webber, of Charlestown, N. H., 

 were most probably indurated entozoon sacs. Many ponds and lakes 

 contain a minute worm, resembling in general form a tadpole, be- 

 longing to the genus Cerca?ia. The species, after living for some 

 time in the water, attach themselves to fishes and other living animals, 

 and, after losing the tail, form for themselves cysts in the integu- 

 ments, and subsequently become transformed into a parasitic worm 

 of the genus Distoma. 



