MORrHOLOGY OF CESTODES FROM POULTRY 27 



are more numerous near the ends of the proglottids. Peripheral 

 nerve cells are widely and irregularly distributed. They are more 

 numerous at the anterior end of the proglottids, especially on the 

 portion that is covered by the backward extension of the preceding 

 segment. 



Excretory System: The excretory system is fairly well devel- 

 oped in this form. The ventral canal (Fig. 14, v ex) is the larger, 

 and has a diameter of 28 to 30/x. A transverse canal unites the 

 two longitudinal canals in each segment. The dorsal canals (Fig. 

 14, d ex) are much smaller, having a diameter of 6 to 8ju, and are 

 not united by transverse connections. The four longitudinal canals 

 extend anteriorly to the scolex where they unite to form a ring 

 which lies in the rostellar sheath around the body of the rostellum. 

 The vas deferens and vagina pass between the dorsal and ventral 

 excretory canals. 



Male Reproductive Organs: The testes vary in number, us- 

 ually from 25 to 40, but in a few cases the number is much greater, 

 being as high as 55 or 60. The testes are quite large, being from 

 40 to SSfi in diameter, and are located in the posterior half of the 

 proglottid (Fig. 14, t), posterior and lateral to the yolk gland. The 

 testes are not arranged in layers, but are grouped in a more or less 

 compact mass almost entirely within the limits of the excretory 

 canals. The vas deferens (Fig. 14, vd) in the anterior third of 

 the proglottid forms a coiled mass at the side of the ovary, from 

 whence it passes laterad to the cirrus pouch as a convoluted tube. 

 The portion of the vas deferens inside the cirrus pouch is coiled, 

 varying in extent in different specimens (Figs. 14, 15). The vas 

 deferens passes into the cirrus. There is no seminal vesicle formed 

 by the vas deferens in the cirrus pouch nor are there any accumu- 

 lations of sperm cells. The cirrus pouch (Fig. 15) is ovoid in 

 shape and is from 75 to 90/i in diameter. The wall is made up of 

 layers of fibers which are both circular and oblique, forming a 

 basket-like network which incloses the cirrus and a portion of the 

 vas deferens. The outer wall of the cirrus pouch forms the inner 

 wall of the deep genital cloaca. The cirrus is a compact structure 

 from 50 to 65^ long and Hned with spines. It is a slightly curved 

 structure passing from the cirrus pouch and curving posteriorly 



