1920.] T. SouTHwELi, & B. Prashad : Phyllohothrium. 3 



contraction was noticed on transferring them to spirit. The great- 

 est breadth of the preserved specimens varies from 3 to 4 mm., 

 and the breadth of the head from 3"5 mm. to 5 mm. In the Hving 

 condition it was noticed that the worms are capable of very great 

 elongation. The great mobility of the bothridia, noted by Van 

 Beneden, was also observed in the living specimens. 



Free proglottides were found in great abundance in the spiral 

 valve of Galeocerdo tigrinis. They varied in shape and degree of 

 maturity. The anterior extremity of the mature proglottid is very 

 much reduced, and the sides curve back from it to the broad and 

 ruffled posterior margin. 



We have nothing to add to the already existing accounts of 

 the external characters of the worm but certain anatomical fea- 

 tures call for remark, as they do not seem to have been noticed 

 before. The reproductive system as seen in a fully mature and 

 detached proglottid is first described, further on the structures as 

 seen in a proglottid still attached to the body of the worm are 

 also considered. 



Male organs. The testes (T) consist of numerous rounded 

 structures occurring from near the anterior pointed portion of the 

 proglottid to behind the genital opening. They occupy the cen- 

 tral field and are situated at a much deeper level than the vitte- 

 line glands which lie external to them. Each testes is about 

 •05 mm. in diameter and is much smaller than is shown by Van 

 Beneden ; moreover the number of testes in each proglottid is 

 much larger than is shown in his figure. From each of the testes 

 leads a fine duct, and the ducts from the various testes unite to- 

 gether to form a single median vas deferens (v.d). This duct is a 

 very much coiled, elongated, tubular structure, which continues to 

 the cirrus sac; the terminal portion forms the ejaculatory duct 

 and the outer end of the tube is continuous with the outer ex- 

 tremity^ of the cirrus sac. At the time of protrusion the ejacula- 

 tory duct is a double tube, the outer tube being the everted part 

 of the cirrus sac (c), while the inner tube is the terminal portion 

 of the vas deferens. This evertible portion— the penis (P) or the 

 cirrus — is unarmed. 



Female organs: — The ovaries (ov.) consist of two large lobes, 

 lying one on each side of the centre line, near the posterior end 

 of the segment ; they are connected with each other by a median 

 isthmus. Each of the lateral halves is double, as has been described 

 by Haswell for P. vagans. The margins of the ovaries are very much 

 crenated. The oviduct (o.d) begins ventral to the isthmus in a 

 pouch-like structure which is known as the ' ' swallowing appar- 

 atus." We have not been able to see in our preparations of P. 

 lactuca the "plug" described by Haswell, and it appears that this 

 structure is absent in P. lactuca. From the '' swallowing apparatus " 

 the oviduct runs backwards, ventrally to the shell gland (S.G.) and 

 the receptaculum seminis (R.S), and then curves upwards and to 

 the dorsal surface, it is then continued forwards dorsally to the va- 

 gina and the isthmus of the ovary to end blindly. In its course it 



