58 BXTLLEIIN 69, UNITED STATES NATIONAL MUSEUM. 



59. Testicles in anterior portion of segment extending entirely across the 



median field as far as the excretory vessels; uterus a transversely elon- 

 gated sac with numerous outpocketiugs anteriorly and posteriorly ; adults 



in birds and mammals BertieUa, p. 62. 



Testicles mostly in the lateral portions of the segment on both sides of the 

 longitudinal excretory vessels, extending from the anterior to the posterior 

 border of the segment; uterus median, bilobed, v^^ith a prolongation pos- 

 teriorly on each side which crosses the longitudinal excretory vessels, 

 and passes forward laterad of and parallel with the latter; adults in 

 birds Aporina, p. 64. 



60. Cortical layer of parenchyma thin ; testicles behind and at sides of female 



glands; adults in mammals and reptiles Oochoristica, p. 84. 



Cortical layer of parenchyma very thick; testicles dorsal, scattered through- 

 out the entire length of the segment 61. 



61. Genital pores unilateral ; genital canals pass between excretory vessels ; 



female glands between dorsal and excretory vessels on pore side of seg- 

 ment; adults in birds , Zschokkeella, p. 65. 



Genital pores alternate; genital canals pass ventral of the excretory vessels; 

 female glands submedian, only slightly displaced toward pore side of 

 segment: adults in monotremes and marsupials Liiistoivia, p. 65. 



62. One testicle in each segment ; strobila circular in cross section with seg- 



mentation distinct only at posterior end ; adults in amphibia. 



Nematotwnia, p. 88. 

 More than one testicle in each segment 63. 



63. Uterus transversely elongated, composed of numerous ascon-like pouches, 



each supplied with a para-uterine organ ; adults in mammals. 



Thysanosoma, p. 66. 



A single and simple qr bilobed uterus with a single para-uterine organ in 



each segment, or two uteri, each with a para-uterine organ 64. 



64. Two uteri in each segment, small, spherical, sac-like, one in each lateral 



half between the dorsal and ventral excretory vessels ; testicles rela- 

 tively few, in two sets, one in each side of the segment in the neighbor- 

 hood of the excretory vessels; ovary small, globose, between the excretory 



vessels on pore side of the segment ; adults in mammals Stilesia, p. 89. 



Uterus single and simple or bilobed; adults in birds 65. 



65. Testicles dorsal of female glands and toward anterior border of segment ; 



genital canals pass ventral of excretory vessels; uterus simple, sac-like, 

 commonly displaced toward side of segment opposite genital pore. 



Anonchotcenia, p. 86. 



Testicles in posterior portion of segment, behind the female glands, may 



also extend forward along sides of latter ; genital canals pass between 



excretory vessels 66. 



66. Uterus tubular and elongated longitudinally, or globular, occupying the 



median line of the segment Rhalydometra, p. 86. 



Uterus when fully developed consisting of two spherical sacs touching in 

 the median line and more or less fused Metroliasthes, p. 87. 



67. Para-uterine organs present 68. 



Para-uterine organs absent . 69. 



68. Uterus single, transversely elongated, undulating, composed of numerous 



ascon-like pouches, each supplied with a para-uterine organ ; adults in 



mammals Thysanosoma, p. 66. 



Two small, spherical uteri in each segment, one on either side, between the 

 dorsal and ventral excretory vessels, each with a single para-uterine 

 organ; adults in mammals . Stilesia, p. 89. 



