214 TAPEWORMS OF HAKES AND RABBITS STILES. 



Egg with thin transparent shells; frequently in egg capsules; in some cases 

 scattered through the segments; head nearly always armed with hooklets on 

 rostelluni; larval stage a cysticercoid ; adults in birds and mammals. 



Dipylidiince (p. 193), 27 

 Anoplocephalince. 1 



5. Ova with well developed pyriform body; genital canals pass dorsally of longi- 



tudinal canals and main nerve trunk (not yet satisfactorily demonstrated for 

 Andrya) 6 



Ova without pyriform body; genital canals pass dorsally of ventral canal and nerve, 

 but ventrally of dorsal canal (not yet demonstrated for Stilesia centripunctata) . 10 



6. Uterus a transverse tube, generally continuous, in some of the double-pored 



forms divided (double), one tube for each ovary, and generally provided with 

 proximal and distal pouches; dorsal canal lies dorsal to dorso-lateral of ventral 



canals ; pedunculated prostatic gland absent 7 



Uterus more like a network in its early stages; afterwards the boundaries of the 

 meshes nearly or quite disappear and the uterus (or uteri) appears like a sac. . 9 



1 The genera of Anoplocephalince may also be determined by the following key, which 

 although simpler than the one given above, is much more artificial : 



Anoplocephalina. 



A. Genital pores single B 



Genital pores double F 



B. Genital pores unilateral or irregularly alternate with decided tendency to 



unilaterality . C 



Genital pores regularly alternate or nearly so; pedunculate prostatic glands 

 absent D 



C. Pores unilateral; testicles unilateral or nearly so in median field opposite pores; 



uterus transverse with proximal and distal pouches; pedunculate prostatic 



gland absent Anoplocephala, 1 1 



Pores irregularly alternate with decided tendency to unilaterality; uterus forms 

 a network in its younger stage, later the meshes become nearly or quite 

 obliterated; testicles extend across the median field to or beyond the ovary; 

 distinct pedunculated round or elongate prostatic gland present. .. Andrya, 26 



D. Egg without pyriform body E. 



Egg with well-developed pyriform body; uterus transverse with thin- walled 



proximal and distal pouches; genital canals pass dorsally of dorsal and ventral 

 canals and main longitudinal nerve trunk Bertia, 14 



E. Uterus single and transverse, without pouches, or double, a cornucopia-like egg pouch 



being present near each ventral canal, the median transverse connecting canal not 

 visible; genital canals pass dorsally of nerve and ventral canal, but ventrally of dor- 

 sal canal (not shown for S. centripunctata) *. Stilesia. 



Uterus transverse but undulate, with thick-walled asconspore or cornucopia-like egg 

 pouches; genital canals pass dorsally of nerve and ventral canal, but ventrally of 

 dorsal canal Thysanosorna. 



F. Egg without pyriform body; uterus transverse and undulate, with thick-walled ascon- 



spore or cornucopia-like egg pouches; genital canals pass dorsally of ventral canals 



and nerves, but ventrally of dorsaj canal Thusanosoma. 



Egg with well- developed pyriform body ; genital canals dorsally of ventral an I 

 dorsal canals and nerves G 



G. Uterus a transverse tube, single or double, with thin-walled egg pouches ; dorsal 



canal dorsal to dorso-lateral of ventral canal ; vagina ventral of cirrus pouch 



on both sides of the segment Cittotcenia, 19 



Uterus reticulate, double; dorsal canal dorsal to dorso-median of ventral canal; vagina 

 ventral of right cirrus pouch, dorsal of left cirrus pouch Moniezia. 



