American Representatives of Distomiun variegatum. 897 



long before thej' attaiii to tlieir largest dimensions, and one may 

 not know that the worm in band, altbough black with contained 

 eggs. is only a small, young individual. Tbe drawings are made 

 from Worms near the maximum size for eacb species, and bear an 

 approximate ratio to tlie measurements of the largest individuals. 

 Each is about twelve times the length of my largest moimted 

 specimen of the species, biit is rather broader in proportion. The 

 shape of the living worm may of course vary continually. The 

 drawings represent worms at rest or killed under the 8ame conditions 

 in a mixture of glacial acetic acid and alcohol. 



For a brief approximate statement of their external appearances 

 and for a provisional means of distinguishing them, I refer to the 

 following table. Nos. 1 and 5 are the extremes and are easy to 

 distinguish by the folding of the uterus. Nos. 2. 3 and 4 are much 

 alike in this respect biit may be distinguished by the size of their 

 festes, ventral siickers or eggs. 



Posterior lateral folds of uterus reaching to level öf pharynx. 



No. 1 — short, broad, thick. 

 Posterior lateral folds reaching only to last testis. 

 Large, lobed testes. 



No. 2 — long, broad, thin. 

 Small testes. 



Small ventral sucker and medium sized egg. 



No. 3 — long, median in breadtli and depth. 

 Large ventral sucker and large egg. 



No. 4 — short. tapering, shick or rounded. 

 No posterior lateral folds to the uterus. 



No. 5 — long, narrow, thick or rounded. 



In Colour the younger worms are lighter, the older darker, 

 due to the brown eggs they contain. The eggs in the first part of 

 the Uterus are latest from the ovary and are of the lightest shade, 

 while the oldest eggs in the distal half of the uterus are deepest in 

 colour. Knowing this, one can offen distinguish overlying folds or 

 proximal and distal parts of the uterus. The colour of the intestinal 

 caeca is offen reddish from the contained frog's blood, or blackish 

 from the disintegrated pigment of the same or from their own eggs 

 that have been swallowed. 



Suckers. The ventral sucker is always smaller than the oral 

 sucker. It is usually a little less than half as broad as the mouth- 



