PARASITIC WORMS — LBIPER AND ATKINSON. 



51 



variation in colours I icing due to age. The birds were taken at South Trinidad (Stat. 

 36). 



External Characters. — The worm is of a dirty white colour. The head is followed 

 by a short neck. The strobila measures from 4* 5 cm. to 5 cm. Each segment slightly 

 overlaps its successor. About the middle of the body the segments are almost as long as 

 they are broad, hut towards the posterior end the breadth considerably exceeds the length. 



Head. — The head (PI. IV, tig. 26) carries four suckers, which occupy ear-shaped 

 projections on its sides. They are not visible from the top. as in the two other species 

 obtained from this bird. The head measures 0 ' 84 mm. from side to side, and 0 " 92 mm. 

 antero-posteriorly. Each sucker is longer than it is broad and measures 0"94mm. 

 Longitudinally and 0 ■ 62 mm. transversely. There is no rostellum and there are no hooks. 



Segments.' The segments described (PL IV, fig. 27) are from about the middle of 

 the worm. Each is slightly wedge-shaped, being narrower in front than behind, the 

 hinder margin overlapping considerably. They measure 0*62 mm. antero-posteriorly, 

 0"6mm. from side to side in front, and 0'82 mm. from side to side behind. 



The genital pores are marginal and unilateral. They measure 0* 14 mm. in 

 length and are somewhat rounded. The cirrus is well developed, unarmed, and 

 measures 0 ' 06 mm. in length. The outer portion of each segment in a stained 

 specimen remains (dear and unstained. The testes and the female organs are confined 

 to the space internal to this. The testes are numerous, numbering 35-50 or more, 

 and are of medium size. The yolk-gland is relatively large and is placed in front 

 of the testes, at the anterior border of each segment. The uterus is a simple sac 

 containing the eggs. Eggs are found only in the latter segments. Two well-marked 

 excretory canals run down either side, externally to the testes and just internally to the 

 cirrus-opening. 



33. Tetrahothnns mtherinae, Leip. and Atk. (PI. IV, figs. 29, 30. Text-fig. 9.) 



Tetrabotlirius rather inae, Leiper and Atkinson, Proc. Zool. Soc, 1914, p. 225. 



Stouter than the preceding species. Head comparatively small. Suckers mostly on the top of the 

 head. The segments overlap their successors by one-third. Testes 30 to 45, bunched in the middle of the 

 segment. Genital organs very characteristic. Cloaca divided into outer and inner portions. There is 

 a large pyriform seminal vesicle internally to the cirrus. 



Host. — Trinidad Petrel [CEstrelata tririitatis) ; small intestine. 



External < 'haracters. — The colour is white. The worm is stouter and thicker than 

 the preceding Cestode. The segments are broad from side to side, and short from 

 before backwards ; and this shape is uniform throughout. There is a comparatively 

 small head, no neck being present, and the segments immediately follow it. These 

 gradually increase in breadth until the worm ends caudally. The genital pores are 

 unilateral and open nearer the ventral than the dorsal aspect. 



I lead.- - The head (PI. IV, fig. 2;)) is comparatively small, and is without hooks or 

 rostellum. There are four suckers, which are placed mostly on the top of the head, 



K 



