The American Eepresentatives of Distomum cygnoides. 417 



occiipy the micldle region of tlie bocly, from the ventral siicker 

 backwards, snrroimding and concealing- the genital glands, and 

 constituting- the chief cause of the opacity of the animal. Close 

 Observation reveals the fact that the intestinal cneca are displaced 

 laterally, so that there is scarcely a fold of the uterus to be 

 discovered between them and the lateral body-walls. This position 

 of the intestine as well as the g-reater thickness of the body are 

 characteristic of transverse sections. The anterior part of the 

 Uterus is generally much distended as in the figure and, whereas in 

 No. 1 there are only two or three transverse folds between vitellaria 

 and ventral sucker, in this species there are five or six. So far as 

 I can judg-e from mounted preparations of the worm the eg-gs of 

 this form are of the same size and shape as in the preceding- one. 



3. Gof'ffodera siniplex Looss. 



Attention was first directed to this form by Bensley in the 

 paper already mentioned. The figure (flg. 1. Photo-microg. of Dis. 

 ci/f/noides var. B) given there is a good representation of a young 

 worm about 5 mm in length. The drawing I give is from an adult 

 7-5 mm long (killed, stained, dehydrated, cleared, mounted). It is 

 drawn to a scale which will represent the relative size of average 

 adults as compared with the other species of the group. Living 

 Worms may be found measuring 12 mm in length, but the greater 

 number vary around 7 or 8 mm. 



This species inhabits the Bull-frog (Rana cateshiana). It 

 resembles No. 2 in a great many respects, and indeed intermediate, 

 transitional stages are not hard to conceive, however difficult they 

 may be to find. In external appearance it is always long and slim, 

 having a pretty uniform breadth, and being somewhat cylindrical. 

 A mounted specimen, 8X"7 mm, uniformly extended throughout its 

 length, measures 1-63 mm to the middle of the ventral sucker 

 and 6-36 mm from this point to the end of the body. The mouth 

 and ventral suckers measure respectively •465 and 620 mm (= 1:1-3 

 to 1-5). The centre of the ovary was 2 mm from the centre of the 

 ventral sucker, and from the anterior end of the ovary to the 

 posterior end of the second testis was 2-6 mm. It resembles No. 2 

 in having the genital glands at a distance from the ventral sucker 

 but, on the other hand, these are separated from each other at a 

 considerable distance. The ovary is offen heart-shaped but in some 



