64 CE\TLON PEARL OYSTER REPORT. 



Eniochobothrium gracile, n. sp. Plate IV., figs. 60 to 62. 



Along with certain specimens of E. javamcum from the intestine of the Rhinoptera 

 javanica captured off Dutch Bay on January 10, 1905, were some small but very 

 remarkable Cestodes which we have named Eniochobothrium gracile. Unfortu- 

 nately but few specimens of each were taken. 



Eniochobothrium gracile measures, according to Mr. HORNELL'S drawing, natural 

 size, 12 millims., but in the few specimens put into spirit none surpassed 5 millims., 

 and the only one mounted attained a length of 3 '5 millims. These specimens, it is 

 true, had all lost their heads, but, as the sketches show, this takes up but a small 

 proportion of the total body length. Possibly they may have shrunk in spirit. 



The head is pyramidal in form, the apex pointing forward (Plate IV., fig. 62). 

 This part, which represents the rostrum, is circular in outline, but at the base of the 

 pyramid the circumference becomes quadrangular and bears at each angle a small but 

 conspicuous sucker ; behind these the head rapidly narrows towards its insertion into 

 the neck. The rostrum is unarmed. 



The drawings made from the fresh specimens show behind the head a short neck 

 of three segments. This is followed by a remarkably expanded portion of the body 

 forming an oval somewhat pointed at both ends (Plate IV., figs. 60 and 62). This 

 expansion consists of some eighteen segments which, beginning behind the neck, 

 gradually increase in width until the ninth or tenth segment and then diminish again 

 until they reach their narrowest at about the eighteenth segment. The posterior 

 edges of these segments are very salient and overlap the succeeding segments, except 

 in the middle line, where there is a break just as there is in front between the right 

 and left sides of an Inverness cape. In fact this portion of the body looks somewhat 

 like the elderly coachmen who figured in the early half and middle of the nineteeth 

 century, encased as they were in innumerable capes, each a little longer than the 

 other, as one penetrated inwards from without. 



Behind this oval portion comes another isthmus, consisting again of about eighteen 

 segments, very much narrower than any in the expanded oval region and very much 

 shorter from before backwards. They are perhaps a little wider than the segments 

 of the neck, but they are very small. 



We can easily imagine how segments can become larger as they are pushed 

 backward by the intercalation of new segments behind the head, but it is not so easy 

 to see how they shrink. The wide large tenth segment of the oval expanded area must 

 gradually dwindle as it becomes in turn the eleventh, twelfth, thirteenth, and finally 

 the eighteenth. There must be an almost sudden shrinkage as the eighteenth 

 passes into the nineteenth segment, and then the bulk of the segments remain about 

 constant and very minute until the thirty-sixth segment is reached (Plate IV., 

 figs. 60 and 61). After this come some six or eight segments which very rapidly 

 increase in size ; so quickly do they grow that each of the last two may equal or even 

 surpass the whole of the rest of the tape-worm 



