PARASITIC WORMS— LEIPER AND ATKINSON. 



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and 0 '8 G mm. dorso- veil trail y. They arc placed on either side of the worm, and not 

 on its dorsal and ventral surfaces. The apex of the head measures 1'56 mm. from side 

 to side and 0'92 mm. from above downwards. 



Segments. — That described is the ninety-seventh segment. The segments are 

 quadrate, their hinder and lateral portions slightly overhanging the following segment 

 by a, short nipple-shaped projection on either side. They are broader from side to side 

 than from before backwards, with the exception of the first few segments. There is a 

 long neck. In a stained specimen the outer portion of each segment stains diffusely 

 with haematoxylin. Measurements: from side to side, l'5mm. ; from before back- 

 wards, I nun. 



The genital pore is surrounded by a slight mound, which includes the aperture for 

 the cirrus and the vaginal opening. The mound usually has an elongation towards the 

 vaginal pore. The opening is placed about mid-way in the segment. The cirrus is 

 extended in nearly all the segments that are mature. It ends in a clubbed, roughened 

 portion having five lobes, but no hooks, and measures 012 mm. in length. The opening- 

 is almost circular and measures 0'02 mm. The vaginal opening is very small, relatively, 

 measuring 0'04 mm. in its greatest breadth and 0'06 mm. in its greatest length. From 

 it a well-marked vagina leads slantingly backwards to the uterus. The female organs 

 ;iic colic, ted just behind the opening, forming a dark staining mass. The uterus is 

 small and is confined to this space. The eggs begin to appear at the fifty-seventh 

 segment, and measure 0'07 mm. The testes are numerous and are scattered throughout 

 the (issue of the segment; there are few on the outer side of the excretory canals. 

 There is no definite arrangement as in the preceding Cestode. The single pair of 

 excretory canals are wide. They lie just outside the junction of the outer and middle 

 thirds of the segment. The ventral surface of the segment seems to bear definite 

 transverse rugae. These may have been caused by contraction, but are more probably 

 a permanent feature. The longitudinal muscular fibres are well marked, but the 

 circular are less distinct. The shape of the genital opening is very distinctive ; as is 

 the shape of the extremity of the cirrus. 



Diphyllohothrium, Cobbold, 1851). 

 23. D ipliyllobothr turn per foliatum, Railliet and Henry, 1912. (Text-fig. 8.) 



Host. — Weddell's Seal (LejJtonyc/tofrs ircddclli) ; small intestine. The parasite 

 occurs in a well-marked tuft at the beginning of the small intestine. The majority of 

 the individuals have their heads beneath the first two or three valvulae conniventes. 

 The Report of the French Antarctic Expedition under Dr. Charcot, 1909, describes 

 the same arrangement of the worms at the ileocaecal valve. 



External Appearance. — The worms measure, on the average, 14 cm. in length, but 

 there is a certain amount of variation in size. The head and some portion of the 



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