52 "TERRA NOVA" EXPEDITION. 



and do not extend for any great distance down the sides. They are not deep and 

 have no overhanging border. 



The head measures 9 mm. in breadth and 0'9 mm. in an antero-posterior direction. 

 The outside measurement of a sucker in its broadest part is 0'42mm., and in its 

 longest axis 0'62mm. The greatest inside measurements are ' 2 mm. by 0'34mm. 

 There is no neck, the head being immediately followed by the segments. 



Set~/in<-'iit$. The segments described (Fig. 30) are those from the head-end of the 

 worm, and later, segments cut in serial sections from nearer the caudal end. Each 

 segment measures l'14mm. from side to side and 0'42mm. antero-posteriorly. The 

 hinder border of the preceding segment overlaps it for over a third of its ventral 

 surface, and it in turn overlaps the following segment. The musculature is exceedingly 

 well developed. There is a clear outer space in a stained specimen and a more deeply 

 staiuiuo- interior containing the generative organs. The testes are numerous, 30 to 45, 



o o o 



and are found internally to the excretory canals. They 

 are bunched more closely together in the middle of the 

 segment and are there difficult to count. A small ovary and 

 yolk-gland are placed in front of them near the anterior 

 sb border of the segment. The genital openings are peculiar. 



FIG. S.Tetralothrliix ,;itl<rr- They are unilateral and open on the side of the segment, 



inae : the terminal organs , , , , -, -, mi 



,, ., .. but more on the ventral than on the dorsal aspect, lliere is 

 of the genital apparatus. 



ec, muscular external a small punctate opening or depression showing signs of 

 portion of cloaca; i<; in- s triation (text-fig. 9, IT). Internally to this there is a well- 



ternal portion ; s, cirrus ; , . , . , . . , n , 



sb cirrus sac marked ring (ic) containing the male and female openings, 



and behind that a very large cirrus (*) and cirrus-sac (*(>). 



The outer opening has an internal measurement of 02 mm. and an external diameter 

 of ' 04 mm. The inner ring has an internal aperture of ' 04 mm. and an external 

 opening of OH mm. The cirrus measures 16 mm., and is unarmed. 



In sections of more mature segments the whole of the interior is taken up by a 

 mass of eggs in a sac-like uterus, which is simple and undivided. Well-marked broad 

 bauds of muscular fibres are present. Two excretory canals run down either side of 

 the segments. The outer and smaller lies very near the edge. The inner, a far wider 

 canal, runs down at a short distance from it internally. 



34. Ti'trnliotlirin* nii-lic.wm, Leip. and Atk. (Text-fig. 10). 



Ti'trabtitltriiix titrlit'soiii, Leiper and Atkinson, Proc. Zuol. Sue., 1'J14, p. '2'25. 



Strobila 3 cm., more slender than in the preceding species. Segments more uniform, only over- 

 lapping slightly. Testes arranged in three distinct sets, very numerous, far in excess of those of the 

 previous forms. 



llofit. Trinidad Petrel (tEi<tn'/<if<t fi-!iiit</f!*) ; intestine. 



External ( '/mmi-frr*. This Cestode is of a dirty white colour, and measures 3 cm. 

 to 3 '5 cm. in length. It is a more slender worm than the preceding, and the segments 



