8 CEYLON PEARL OYSTER REPORT. 



collar, such as a lower-form Eton boy wears. The free edge of this collar projects 

 backwards for a variable distance. In the living form drawn by one of us the collar 

 is far more extensive than it appears to be in the preserved specimens ; it may have 

 shrunk in the preserving fluids. In the one which was cut longitudinally there is 

 evidence of such shrinking, especially at the base of the head. 



The proglottides are at first extremely narrow, but lengthen out until about the 

 centre of the body they are as long as they are broad. Posteriorly they 

 may be three times as long as they are broad, and here they have the some- 

 what melon-seed outline of the D. cucumerina. In front of the last three or four 

 proglottides, each has slightly convex sides, and the posterior edge is slightly broader 

 than the anterior, so that the posterior edge of each proglottis extends a little beyond 

 the anterior edge of the next behind it, but it does not overlap. The junction of two 

 proglottides is always in one plane. The transverse section is almost circular, the 

 dorso- ventral axis being but little shorter than the ventral. 



The genital pore is lateral. The penis is armed with innumerable minute recurved 

 spines. The yolk glands are very definitely arranged in a layer external to the other 

 reproductive organs. As they stain deeply they form a conspicuous ring just inside 

 the muscular layer, which is thin. Posteriorly they converge to a spot near which 

 the ovary probably lies. The uterus is thick walled. The testes occupy a large part 

 of the body within the vitellaria, and there is a conspicuous vesicula seminalis, 

 crowded with spermatozoa. There were only two specimens available for study ; one 

 of these was mounted whole, the other was partially sectionized, but in none of the 

 proglottides cut were there eggs in the uterus. 



Other specimens of the species Tiarabothriwn javanicum came from the intestine 

 of the Trygon walga. The bothridia were not very distinct, and the number of 

 areolas could not be made out. In one specimen, which was mounted, the breaking 

 up of the longitudinal muscles as they entered the head was very clearly shown. The 

 proglottides are broadest in the middle and narrow towards each end, and the 

 posterior end is no wider than, and does not overlap, the anterior end of the next 

 succeeding proglottis. There is no unsegmented neck, the first proglottis coming 

 immediately behind the head, and the anterior half of the body is broadest at about 

 the region between the eighth and the sixteenth proglottis. The cirrus is armed with 

 spines. The collar is small. 



Habitat : Intestine of Rhinoptera javanica. 



RHYNCHOBATUS DJEDDENSIS, FOKSK. 

 A ray common throughout the Indian Ocean, from the Red Sea to Sumatra. 



Tetrarhynchus rhynchobatidis, n. sp. Plate IV., figs. 69, 70, and 71. 

 The Tamil name for R. djeddensis is " Pal-ulluvi," the Sinhalese " Kiri-uluwa," or 

 "Uluwa mora." Both "pal" and "kiri" signify milk and refer to the milk-white spots 



