56 BULLETIN 69, UNITED STATES NATIONAL MUSEUM. 



Base of cirrus not provided with spines in special poclvets; genital canals 



pass dorsiil of excretory vessels 30. 



34. Segments numerous, rarely less than 30 ; neck present ; genital pores irregu- 

 larly alternate near anterior border of segment; testicles numerous, 

 posterior of female glands or also laterally on both sides of the latter; 

 uterus a simple sac, or incompletely divided into numerous small com- 

 municating compartments Choanotcenia, p. 74 



Segments less than 30 in number; neck absent; genital pores regularly 



alternate ._ 35. 



85. Testicles in posterior portion of segment ; cirrus pouch short. 



AiiKeltotcenia, p. SO. 



Testicles lateral in position toward the pore side of the segment; cirrus 



pouch very long Leptotcenia, p. 81. 



36. Testicles, 12 or more in each segment Lateriporus, p. 73. 



Testicles, 1 to 4 in each segment 37 (Hymenolepidinae). 



37. Testicles, 4 in each segment OUgorcMs, p. 89. 



Testicles. 1 to 3 in each segment 38. 



38. Testicles. 3 in each segment 39 (Hymenolepis). 



Testicles, 1 or 2 in each segment 40. 



39. Entire surface of suckers armed with minute spines, or (generally) un- 



armed; sacculus accessorius usually absent HynicnoJepis s. str.. p. 90. 



Suckers armed on borders and in the middle with small booklets ; sacculus 

 accessorius always present Echinocotyle, p. 98. 



40. Testicles, 2 in each segment; entire surface of suckers armed with minute 



spines, or unarmed; rostellar hooks with long dorsal and short ventral 

 roots (or exceptionally with very short dorsal root, and with ventral 



root nearly as long as the blade) Dioi'chis, p. 98. 



One testicle in eacli segment; suckers (?) unarmed; rostellar hooks with 

 ventral root as long or nearly as long as the blade; strobila small and 

 slender Aploparaksis, p. 99. 



41. Genital pores unilateral 42. 



Genital pores alternate : 45. 



42. Ivoot of cirrus with one or two pairs of powerful spines lying in special 



pockets ; testicles few ; genital canals pass between the longitudinal ex- 

 cretory vessels Gryporliynclnis, p. 83. 



Spiniferous sacs at base of cirrus lacking 43. 



43. No testicles in front of female glands, but usually very numerous behind and 



at the sides; rostellar hooks with long dorsal and short ventral roots; 



genital canals pass dorsal of excretory vessels and nerve Dilepis, p. 71. 



Testicles entirely surrounding the female glands, or limited to the region 

 In front of the female glands 44. 



44. Testicles very numerous, entirely surrounding the female glands; cirrus 



pouch communicating with the genital cloaca by a narrow canal opening 

 ■ upon a large papilla ; rostellar hooks with a very large dorsal root and 



small hook portion Cyclorchida, p. 82. 



Testicles limited to the region in front of female glaudg ProorcMda, p. 82. 



45. Tesjicles scattered throughout entire dorsal portion of medullary paren- 



chyma ; ovary and yolk gland surrounded by a ring-like uterus with 

 secondary branches ; genital canals pass between excretory vessels ; longi- 

 tudinal musculature in three layers Cyclustera, p. 81. 



Testicles, in lateral or posterior portions of segment only 46. 



46. Testicles in lateral -portions of segment only 47. 



Testicles in posterior portion of segment only 48. 



