220 ILLINOIS BIOLOGICAL MONOGRAPHS (508 



EXPLANATION OF PLATE 



Fig. 59. Bothriocephalus scorpii, outline of mature segments. 



Fig. 60. Bothriocephalus scorpii, toto of same specimen. 



Fig. 61. Bothriocephalus scorpii, portion of strobila showing excretory vessels. 



Fig. 62. Bothriocephalus manubriformis, anterior primary segment. 



Fig. 63. Abothrium rugosum, terminal excretory vesicle. 



Fig. 64. Abothrium crassum, anterior segments of strobila from Coregonus clupeiformis, toto. 



