404 J. STAFFORD, 



2.75 miu by 0.875 mm, ])ut I have measured living specimeiis 3.675 mm 

 long and proportionately broad. Measuremeuts of differeut individuals, 

 unless they are distorted by pressure, are likely to bear pretty ac- 

 curately the same proportions ; for, as indicated in the specific name, 

 tliis is a very quiet little creature, that may rest inactive for con- 

 sidcrable time, and, wlien it does move, it is with slow and graceful 

 raovements that cbange its dimensions only to a slight extent, chiefly 

 in extending and withdravving the anterior end and not at all in vio- 

 leutly flopping back and forward, wriggling and disfiguring itself as 

 some otber frog-treraatodes do. The body is cylindrical, as shown by 

 the circular transversal sections, the posterior end blunt or rounded 

 and the anterior taperiug. The colour is white, except in the middle 

 region of the posterior half which is brown — due to the eggs. This 

 worm " is not at all evidently exposed when the in testine of the frog 

 is slit open. They are easy to overlook even when one directs bis 

 attention to a small surface. Often a minute light brown speek is all 

 that can guide one's forceps to the object of bis search. It may be 

 that this is the cause of our worm's having escaped the attention of 

 helminthologists so long; or, on the other band, it may be that it is 

 only local in its occurrence, or that it has been mistaken for Distomum 

 endolohum to which I think it bears considerable resemblance. 



The iuteguraeut is furuished with a thick cuticle containing except 

 at the anterior and posterior ends small backwardly slanting spines. 

 These are arranged in longitudinal rows with great regularity. The 

 rows are perhaps 15 /< apart and the spines of every second row are 

 opposite the Spaces between those of the first and third rows. Be- 

 tween two spines of the same longitudinal row is a Space of 30 /<, 

 but this may vary a little according to the region of the body. The 

 spines themselves appear narrow when looked at on the edge of the 

 body, but more scale like when viewed at right angles to the surface 

 of the body; they seem to be fixed to a circular basal plate and are 

 15 /t in length. 



The fixing organs are an anterior mouth-sucker and a ventral 

 sucker of smaller dimensions. The mouth sucker, in the mounted 

 specinien above described is 0.260 mm broad while the ventral sucker 

 measures 0.175 mm. The ventral sucker is placed 1 mm from the 

 anterior end and 1.75 mm from the posterior end, while between the 

 two suckers is a space of 0.875 mm. 



In a living worm 3.675 mm in length the anterior sucker measured 

 0.350 mm across and the ventral sucker 0.210 mm. From the anterior 



