PARASITIC WORMS— LEIPER AND ATKINSON. 



I 1 



The segment described measures I -()4 mm. from before backwards, 0*44 mm. in its 

 broadest side to side measurement, and 0"34 mm. in width at the caudal end. The 

 surfaces of the segments are not folded. Two excretory canals run down either side 

 of the segment ; the inner pair run down practically alongside the female organs, 

 while the outer pair are separated from the others by a, considerable interval. The 

 testes are distributed between and outside these canals. 



21. Dibothriocephalus lashleyi, Leip. and Atk. (PL V, tigs. 40. 41.) 



Dibotlirioce.phalus laslileyi, Leiper and Atkinson, Proc. Zoo]. Soc, 11>14, p. '2'24. 



3 to 4 cm. in length. Young segments quadrate. Mature segments ."> to 4 times as long as broad. 

 Head I "2 mm. long and 0"77 mm. broad. Suckers situated laterally, almost circular, and not extending 

 far down the head. Eggs first appear at the 14th segment, and measure 0 ' 06 mm. in diameter. The 

 testes extend inwards in each segment in single series of three. 



Host. — WeddelFs Sea. I (Lepto/u/ehotes weddelli). Tins Cestode, like the previous 

 one, occurs in the upper part of the small intestine in large numbers. 



External Characters.— The colour varies; the head and some part of the anterior 

 end are white, but where the segments begin to elongate the colour becomes pearly 

 grey. This Cestode is larger than the preceding and measures 3 cm. to 4 cm. 

 in length. The surface is folded, but this is probably due to contraction. The 

 anterior segments are quadrate and shortened antero-posteriorly, broader from side 

 to side than from before backwards. The hinder segments are enormously elongated 

 and their length is three to four times as great as their breadth. The head is some- 

 what conical, ending in a point, and is less markedly clubbed than in the preceding 

 species. 



Head (PI. V, tig. 40). — The head is relatively small, measuring 1*2 mm. in its 

 greatest length, while its greatest breadth is 077 mm. The central portion, between 

 the two suckers, terminates as a nipple-shaped projection. No rostellum and no hooks 

 are present. The suckers are placed on either side, not on the dorsal and ventral surfaces. 

 They are almost circular and do not run down the head for any considerable distance. 

 They measure 0 ' 24 mm. antero-posteriorly and 0* 17 mm. from side to side. They 

 are depressions, and have not the fold found in the following species (text-fig. 11). 

 The head is continuous with the neck, which is short, the worm rapidly becoming 

 segmented. 



Segments (Fig. 41). — In the strobila examined the eggs first appear at the 

 fourteenth segment. The anterior of the segments which are mature are broader 

 from side to side than from before backwards. The posterior are greatly elongated. 

 The former measure 14mm. from side to side and 0'6mm. from before backwards. 

 The latter measure 1*8 mm. from before backwards, 0*92 mm. from side to side at the 

 cephalic end. and 0'58mm. at the caudal end. 



The genital pore is in the middle line and is a simple opening : it is placed nearer 

 the cephalic than the caudal border of the segment. It consists of the cloaca! opening 



