American Representatives of Distomum variegatum. 899 



oviduct, which from tliis point onwards is called the Uterus. The 

 first Short piece of the latter may be filled with sperm (recept. sem. 

 uterinum), but the rest, in adults, is filled with eggs. 



A very useful character in this group of worms is the arrange- 

 ment of the uterus, which one might at first be inclined to 

 think unimportant upon the ground that the Uterus is a very long 

 tube, fixed at both ends and with the intermediate part free to 

 take Avhatever position niay be accorded it by the other organs. 

 It is however the constancy in size, shape and position of other 

 Organs as ovary, festes, intestine, which necessitates a particular 

 mode of folding of the uterus, and, when we find this associated with 

 other constant differences, we can afford to attribute to it a higher 

 value. The general course of the uterus is from the ovary backwards, 

 through the niiddle, dorsal part of the body to the posterior end, 

 where it makes a löop forwards and back, first on one side and then 

 on the other, outside of each intestinal caecum i. e. between the 

 intestine and the lateral wall of the body ; after reaching the middle 

 of the posterior end again, it runs forwards, more towards the ventral 

 surface, accompanying the first part of its course as far as the ovary, 

 beyond which it proceeds alone to the external genital opening, 

 below the pharynx. The parts of the uterus belonging to the middle 

 longitudinal axis are not straight, except in young worms, but thrown 

 into shorter or longer transverse folds or spirals. In No. 1 it forms 

 a broad, deep-brown, median band, thrown into a large spiral in 

 front, but with only a few small twists behind. In all the others 

 there is a tolerable similarity in the part anterior to the ovary, but 

 the middle portion always forms a broad band or several small folds, 

 Crossing the body between the festes, and between the anterior testis 

 and the ovary. In No. 1 the posterior lateral loops reach forwards, 

 nearly, or quite, to the level of the pharynx ; in Nos. 2, 3 and 4 they 

 extend only to the posterior testis ; in No. 5 they are entirely absent, 

 but the descending limb of the uterus forms a coil on one side, and 

 the ascending a coil on the other — both between the intestinal caeca. 



The ovary may be median, right, or left in position, and is 

 characteristically lobed only in No. 2. In Nos. 1 and. 3 it may be 

 compact or obscurely lobed, and in Nos. 4 and 5 it is round or 

 elliptical. 



The festes, in their size, shape, and position, offer better points 

 of recognition. In No. 1 they are long, narrow organs, situated side 

 by side in the posterior part of the body. In No. 2 one testis is 



