PAKASITIC WORMS LEIPER AND ATKINSON. 4:5 



and 0'86 mm. dorso-ventrally. They are placed on cither side <>!' the worm, and nut 



mi its dorsal and \eiilral surfaces. Tlie apex of the head measures r.'iC. linn, from side 

 to side and (VS)'J inni. from above downwards. 



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

 <|iiadrate. their hinder and lateral portions slightly overhanging the following segment 

 I iy a short nipple-shaped projertion on either side. They are broader from side to side 

 than from liefore Backwards, with the exception of the first few segments. There is a 

 lmi'4 neck. In a stained specimen the outer portion of each segment stains diffusely 

 \\nli haematox vlin. Measurements: from side to side, 1 '5 mm. ; from before back- 

 wards. I mm. 



The genital pore is surrounded liv a slight mound, which includes the aperture tor 

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

 \aninal pore. The opening is placed aliout mid-way in the segment. The cirrus is 

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

 portion having live lolies. hut no hooks, and measures <) 1:2 mm. in length. The opening 

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

 measuring 0'0-tmm. in its greatest lireadth and O'OG mm. in its greatest length. From 

 it a well-marked \agina leads slantingly liackwards to the uterus. The female organs 

 are collected 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 O'OTnim. The testes are numerous and are scattered throughout 

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

 There is no definite arrangement as in the preceding ( 'estode. 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. 



l>i/>/i////ii/n>f/iriiiiii, (obbold. 1859. 

 2:\. IH/>/ii//l<>/n>//ir!iiiii /H'l-t'o/ntfinii. Railliet and Henry, I!) 1:2. (Text-fig. S.) 



llnxt. Weddell's Seal (Leptonychotes weddelli); small intestine. The parasite 

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

 I he individuals have their heads beneath the first two or three \al\nlae coniiiventes. 

 The Report of the I'Vendi Antarctic Expedition under Dr. Charcot. I '.)()!). describes 

 the same arrangement of the worms at the ileocaecal valve. 



I-'.. it, nml Appearance. The worms measure, on the average. 14 cm. in length, but 

 there is a certain amount of variation in si/e. The head and some portion of the 



I 



