PLATE IV. 



Fig. 22. — Tetrabothrius wrigJiti, Leiper and Atkinson ; ex Pygoscelis adeliae. Complete but immature 

 strobila, showing characteristic suckers, and the arrangement of the testes in the segments. 



Fig. 23. — Anomotaenia zederi, ex Aptenodytes forsteri. Immature form from cyst. 



Fig. 24. — A. zederi. Cyst dissected out from intestinal wall and showing long neck and opening into 

 lumen of the gut of the host. 



Fig. 25. — Tetrabothrius nelsoni, Leiper and Atkinson; ex Phoebetria palpebrata. Segment, showing a, 

 genital atrium ; b, vas deferens ; c, cirrus ; t, testes ; v, vagina ; vs, vesicula seminalis. 



Fig. 26. — Tetrabothrius creani, Leiper and Atkinson ; ex CEstrelata trinitatis ; head, showing suckers. 



Fig. 27. — T. creani. Segments. 



Fig. 28. — Tetrabothrius priestleyi, Leiper and Atkinson ; ex Frigate Bird (Fregata aquila or F. artel). 

 Immature segments ; c, cloaca ; sp, cirrus ; t, testes. 



Fig. 29. — Tetrabothrius catherinae, Leiper and Atkinson ; ex CEstrelata trinitatis ; scolex. 



Fig. 30. — T. catherinae. Segments ; c, cloaca ; sp, cirrus ; t, testes. 



Fig. 31. — Tetrabothrius cylindraceus, ex Megalestris maceormicki. Segments, showing horse-shoe arrange- 

 ment of testes ; c, cloaca ; sp, cirrus ; t, testes ; yg, yolk-gland. 



