DURING HIS SOJOURN IN THE WESTERN PACIFIC. 545 



Roughly speaking the head is hour-glass shaped or perhaps it more closely resembles 

 a box for throwing dice. 



The length of the head is a trifle under 1 mm. and its breadth averages about 

 half its length, the length of the whole animal is from 20 to 30 mm. The pro- 

 glottides are flattened anteriorly, but posteriorly they swell out and assume a some- 

 what bolster-like appearance (Fig. 11, Plate LV.). They are in no part separated one 

 from another by deep furrows and there is no projecting lip overlapping their anterior 

 end. 



The four primary suckers which lie on the anterior face at the base of the hooks 

 are round (Fig. 12, Plate LV.). The third bothriuni is very much smaller than the two 

 which lie in front of it and is separated from the second by a very slight ridge. 



The water vascular system makes a mesh-work in the head which reaches to the 

 extreme anterior limit. Both ventral and dorsal cord persist through the mature 

 proglottides but the ventral one is a good deal larger than the dorsal one. 



The parenchyma of the body is loose and in places takes up very little stain 

 and has a clear appearance. 



The reproductive organs correspond in all essentials with those described by Zschokke 

 in other species of the same genus. The lumen of the vagina is lined by what look 

 like cilia and it is unusually spacious. The cirrhus is provided with rows of large 

 spines, much larger than those in any other species of which I have seen figures. 



The specimens at my disposal were too few in number to make sections in all 

 planes of the head and I have been unable to work out the details of the muscles 

 in this region. Certain of the longitudinal muscles however pass from the head into 

 the neck and these are arranged in eight symmetrical bundles, each bundle seems to 

 lie in a sheath and the whole i-ecalls a somewhat similar structure in Tetrarhynchus. 



The following is a short diagnosis of the new species : 



CalUohothrium aetiobatis, sp. nov. 



This species is characterized by the shape of the head, which is like a dice-box, 

 narrow in the middle and broader at each end. The hooks are bifurcated and hollow 

 at the base. The posterior bothrium is very small and only separated from the 

 middle one by a very insignificant lip. The suckers on the anterior face of the head 

 are circular, and the muscles running from the head through the neck are eight in 

 number and lie in sacs. The penis is armed by unusually large spines, which are 

 slightly curved. 



Habit.\T. Found in the intestine of Aetiobatis imrinari Euphras. in the region of 

 the spiral valve. 



III. ADELOBOTHRIUM AETIOBATIDIS, n. gen. et sp. 



Of the two tape-worms which were found in the intestine of Aetiobatis narinari 

 Euphras., Adelobothrium aetiobatidis is by far the commoner. I have spent a consider- 

 able time in trying to identify this Cestode with some already described form, but 

 neither in the writings of P.-J. van Beneden, Orley, Zschokke or Linton who describes 



