MORPHOLOGY OF CESTODES FROM POULTRY 37 



in Structure and size, 14 to ISju, in diameter. Onchospheric hooks 

 6 to 7/1 long. Egg capsules in groups of 6 to 12 or more, em- 

 bedded in a fibi'ous gelatinous mass. 



In the living specimens very little difference can be noticed 

 except in size of the species D. tetragona and D. echinohothrida. 

 They are both quite transparent and appear much alike in every 

 respect in external appearance, except that D. tetragona is slightly 

 more transparent, while the oldest segments of D. echinohothrida 

 have very distinct median constrictions between them, appearing 

 almost as a series of openings. 



The chief differences between D. tetragona and D. echinohoth- 

 rida are that in the latter the animal is larger, the hooks are more 

 numerous and larger, and the structure and size of the cirrus 

 pouches show a very distinct difference. There is also a difference 

 in the pathological effect of these spiny-suckered forms. D. echino- 

 hothrida produces large nodules or ulcers in the intestinal 

 wall. The scolex bores through the mucosa of the intestine and 

 in some cases nearly through the muscular coats. This disease 

 in fowls is termed "nodular t^eniasis", as described by Moore 

 (1895: 1), and is often mistaken for other diseases. 



3. Davainea cesticillus (Molin 1858) Blanchard 1891 



Diagnosis: Length 10 to 125 mm. Maximum width 1.5 to 

 3 mm. Head cylindrical (Fig. 28), sometimes spheriodal, 0.3 to 

 0.6 mm. wide and 0.2 to 0.4 mm. long. Suckers unarmed, about 

 100/x in diameter. Rostellum broad and flat or hemispherical, 0.25 

 to 0.35 mm. wide, armed with a crown of 200 to 300 hooks which 

 are very unstable and easily lost, arranged in two ranks. Hooks 

 (Fig. 29) 8 to 12/1 long with short dorsal root and long ventral 

 root. Neck very short. Anterior segments three to five times 

 as broad as long; the following increase in size until they become 

 equal in length and breadth and finally even longer than broad; 

 borders overlapping. Genital pores irregularly alternate, one in 

 each segment, somewhat in front of middle of lateral margin in 

 young segments and nearer the middle in older segments. Vagina 

 and cirrus pouch pass dorsal of the two excretory canals and 

 , nerve. 



