40 JOHN E. GUTBERLET 



segments swollen into prominent seminal receptacle (Fig. 18, sr) 

 which extends forward to anterior border of segment and inward 

 considerable distance beyond proximal end of cirrus pouch. Ovary 

 faintly bilobed or trilobed in posterior half of proglottid. Yolk 

 gland spherical or ovoid, 30 to 40/x in diameter, situated near median 

 line of segment, posterior and dorsal of ovary. Uterus at first 

 solid cord of cells extending transversely across segment along 

 anterior border of ovary; becomes hollowed out and grows back- 

 ward on dorsal side of ovary; in gravid segments occupies nearly 

 entire segment and filled with eggs. Eggs (Fig. 27) in gravid 

 uterus spherical or oval, with four thin membranes, the two middle 

 membranes often approximate to form thick layer which shows 

 somewhat of a cellular or coarse granular structure. Diameter of 

 outer membrane 36 by 36/i to 75 by 70[i, of outer middle mem- 

 brane 30 by SOfx to 65 by 6O/-1, of inner middle membrane 26 by 

 26;u to 40 by 35/u,, of inner membrane 24 by 16/^ to 29 by 2lfi. This 

 membrane often lies so close to onchosphere that it can scarcely 

 be distinguished from edge of embryo. Onchosphere is 18 by 14 

 to 27 by 19/A in diameter; length of embryonal hooks 10 to 12;U,. 

 This form is thread-like and usually occurs in great numbers. 

 It is very delicate and fragile and can be recognized by that fact 

 alone, as it is the most fragile of the chicken forms known. 



SUMMARY 



1. By morphological comparison of the cysticercoids produced 

 experimentally in flies and adult of Choanatocnia infundibuliformis 

 they are shown to be identical. 



2. Morphological points noted are the presence of minute 

 booklets on the suckers and entire surface of scolex in Choanatcenia 

 infundibuliformis. The manner of development of uterus in the 

 same species is by means of a blind tube which grows in size, 

 forming pockets, and later breaks up into small compartments. 

 In Davainea tctragona the genital pores were found to occur irreg- 

 ularly alternate in the proglottids. The hooks on the rostellum 

 of Davainea cesticillus were found to vary in length from 8 to 

 12ju.. The uterus in development first appears as a solid cord of 

 cells which becomes hollow and in growing forms pockets, fiUing 

 the entire proglottid. 



