CESTODE AND NEMATODE PARASITES. 81 



Echeneibothrium trygonis, n. sp. Plate VI., fig. 100. 



This species is much more delicate and slender "than E. minimum. It measures 

 from 8 millims. to 15 millims., and its greatest breadth is about 0*3 millim., if we 

 leave out of account the head, which, when the bothridia are turned out, may attain 

 the width of nearly 1 millim. 



The head does not bear the bothridia on stalks, but the neck passes into the head 

 like the stem of a goblet into the bowl. The head is, in fact, rather like the seat of 

 those three-legged camp-stools upon which artists sometimes sit, only there are four 

 instead of three legs. The bothridia face inwards, are deeply hollowed, and acting 

 together must form a very effective sucker. 



On the inner face of each bothridium are seven or eight areolas which stretch 

 across the bothridium, and thus there is no median longitudinal line. 



The head is carried on a stout unsegmented neck, which is a good deal broader than 

 the succeeding segmented part. The proglottides, in fact, do not become thicker as 

 they become posterior ; the anterior and posterior edges of each proglottis are of the 

 same width, and the ripe posterior proglottides are loosely attached to one another, 

 like so many sausages, the medium which keeps them together being apparently 

 the cuticle. In this region they are some five times as long as they are broad. The 

 stained specimens showed no detail of structure and the specimens were too few to 

 cut into sections. 



Diagnosis of Echeneibothrium trygonis : 



Delicate slender form. The four bothridia spring from the neck with no stalk, and 

 bear a single row of seven or eight transverse areolas. The posterior proglottides 

 get thinner as they get older. 



Habitat : The intestine of Trygon walga. 



Eclieneibothrium walga, n. sp. Plate VI., fig. 101. 



This very delicate little tapeworm was found amongst a collection of Tylocephalum 

 trygonis and Echeneibothrium minimum. Unfortunately but one specimen was 

 taken. This measures 7 millims. in length and about 0*2 millim. in breadth. 

 The posterior proglottides are ripe and the animal is probably full grown. 



The head breaks up into four long stalks, each bearing two bothridia or rather 

 two halves of a bothridium. The. stalks appear to be permanently about 1 millim. 

 long, though doubtless they may expand and contract within narrow limits. Each 

 of the half bothridia faces the other and they somewhat resemble the clasping 

 appearance of a Gecko's toes. They each contain a double row of some twelve areolas 

 which are not rounded off towards the longitudinal median partition. Numerous 

 muscle strands pass into each stalk after they have made a cruciform plexus in 

 the head. 



There is scarcely any neck, the narrow, straight-sided proglottides appear close 

 behind the head. About half way along the body the proglottides are square, whilst 



M 



