1918.] T. Southwell & B. Prasiiad : Parasites of Hil-a. 79 



hooks being distributed principally on the outer surface. Anterior 

 segments shallow and numerous. Last segment much longer than 

 head. Total number of segments about 232. Genital apertures ir- 

 regularly alternate, and situated about the posterior third of the prog- 

 lottid. Length of worm 11-5 cms. Posterior segments separating in 

 two's and three's. 



Habitat. — The large intestine of Carcharinus ganr/eticvs (Miill. and 

 Henle). Khulna, district Khulna, Bengal, 21st October 1917. Eleven 

 adult specimens, several young forms just emerged from the cyst, 

 and three cystic forms. No. Z.E.V. "—^ in the collection of the 

 Indian Museum. 



Observations were made on the adult living worms and also on the 

 free proglottides, in fresh water. Later on, these were preserved in 

 corrosive acetic solution. Specimens were mounted stained whole 

 with borax carmine, and also unstained. Sections were not found 

 necessary as the anatomy could easily be determined from the mounted 

 specimens. The head is large compared with the size of the worm and 

 measures 4-2 mm. in length. The breadth of the anterior extremity 

 is 2-6 mm., and of the posterior extremity 1-4 mm. Length of both- 

 ridia 1-8 mm. Length of proboscides 2-1 mm. Length of proboscis 

 sacs 1-6 mm. 



The bothridia (B) are paired, approximated anteriorly and widely 

 separated posteriorly (plate iv, fig. 2). They are round in shape, 

 having entire margins, and sucker-like external surfaces. The probos- 

 cides (P) are four in number ; the armed portion is very short, with 

 an equal length unarmed and very long tubes connecting them to 

 the proboscis sacs (P. S). The hooks (plate iv, fig. 2 a — e) are of four 

 types arranged in oblique rings, the larger ones being disposed along 

 the outer margins. As usual, the hooks towards the base of the pro- 

 boscides are much smaller than the rest. 



The neck is short, measuring only 2-2 mm. It is flattened and not 

 cyhndrical. The anterior proglottides are shallow and numerous. 

 The posterior proglottides are much longer than broad, measuring 5-1 

 mm. by 1-3 mm. The total number of proglottides is about 232. The 

 male genital organs appear first. The female organs are to be seen only 

 in the last few proglottides. Of the male organs, the testes are first 

 visible about the middle of the w^orm. The genital aperture is situated 

 about the posterior third of the proglottis, and the male aperture is 

 immediately in front of that of the female. 



Male organs (plate iv, fig. 4). — These consist of a large number of 

 testes (T) occupying the greater part of the mature proglottid. They 

 first appear laterally. From each of these is given off a minute tubule ; 

 these unite later to form the vas deferens (V. D). This is a thick coiled 

 tube originating a little in front of the ovaries and opening directly into 

 the cirrus sac (C). The vesicula seminalis (V. S) is a bag-like structure 

 which opens close to the junction of the vas deferens and the cirrus 

 sac. The penis is fairly long and lies coiled up in the spacious cirrus 

 sac. We could not distinguish any armature. 



Female organs (plate iv, fig. 4). — The ovaries (Ov) are paired and 

 lie one on each side of the centre line, posteriorly. From each is 



f2 



