MORPHOLOGY OF CESTODES FROM POULTRY 25 



occupies anterior portion of middle field of proglottid in front of 

 shell gland. Large yolk gland posterior to ovary and shell gland, 

 irregular in shape, elongated transversely, with convex ventral sur- 

 face and concave dorsal surface. Uterus (Fig. 16, ti) developed 

 as tube between anterior and ventral lobes of ovary. Gravid uterus 

 fills up most of proglottid, extending beyond excretory canals on 

 each side. Eggs oval (Fig. 7), with very thin membrane next em- 

 bryo, followed by thick, smooth membrane 40 by 32[x to 45 by 36/* 

 in diameter, and one or two outer membranes, very thin and wrink- 

 led in preserved material. Diameter of outer membrane 65 by 40/* 

 to 60 by 45ft ; at each pole of outer membrane a delicate appendage. 

 Embryonal hooks 18/* long. Embryo 32 by 22ju, in diameter. 



2. Morphology: The scolex of the living worm shows up 

 very prominently and can be used as a distinguishing feature. 

 When first removed from the intestinal wall the suckers appear 

 distinct and the neck is much narrower than the scolex. Soon 

 after the removal it often contracts and takes on the appearance of 

 a flattened bulb which includes the neck and anterior segments 

 (Fig. 1). This feature is characteristic of this species and is a 

 factor which alone assists very materially in distinguishing it from 

 others that occur in chickens. 



The rostrum or crown of the scolex is somewhat pointed when 

 the rostellum is enclosed within its sheath (Fig. 2). The rostellum 

 is an ovoid structure with a bulbous expansion at its anterior end. 

 It has a length of 140|U. and a breadth of 60 to 65/i at its anterior 

 end. A crown of 18 hooks is arranged in a single row around the 

 bulbular anterior end. The structure of the wall is of a fibrous 

 nature and presents a transversely striated appearance due to con- 

 traction. In the interior of the rostellum the structure is a con- 

 nective tissue mass with few cells, some of which possess long 

 processes. The hooks (Fig. 8) are SO/n in length with a long dorsal 

 root and a short ventral root. 



The rostellar sheath or sac (Fig. 3, rs) into which the rostel- 

 lum is withdrawn is oval in shape and 230 to 240/a in length by 80 

 to 90)u, in width at its broadest point. Histologically, the structure 

 is that of a fibrous connective tissue type with spherical and spindle- 

 shaped cells. The cells coming in contact with the rostellum. as 



