no ILLINOIS BIOLOGICAL MONOGRAPHS [110 



DESCRIPTION OF PLATE 



Fig. 47. — Tetracotyle pipientis; ventral view, showing digestive tract and genital system. 



X 105. 

 Fig. 48. — Tetracotyle pipientis; diagram of the excretory system, with excretory granular 



inclusions. X 105. 

 Fig. 49. — Cercaria ptychocheilus; ventral view, including digestive, excretory and genital 



systems. X 105. 

 Fig. 50. — Cercaria ptychocheilus; sketch of encysted worm. X 25. 



Fig. 51. — Cercaria ptychocheilus; sketch of ruptured cyst with attachment annulus. X 25. 

 Fig. 52. — Cercaria ptychocheilus; detail of genital system. X 165. 

 Fig. 53. — Cercaria ptychocheilus; nervous system. X 330. 



Fig. 54. — Cercaria ptychocheilus; transverse section thru middle of body. X 540. 

 Fig. 55. — Cercaria crenata; dorsal view. X 170. 



Figs. 56, 57. — Cercaria crenata; ventral and lateral views of stylet. X 540. 

 Fig. 58. — Cercaria crenata; sporoc3^st. X 54. 

 Fig. 59. — Cercaria crenata; detail of genitalia. X 170. 

 Fig. 60. — Cercaria glandidosa; ventral view. X 370. 

 Fig. 61. — Cercaria glandidosa; ventral view of stylet. X 370. 

 Fig. 62. — Cercaria glandulosa; salivary and cystogenous glands. X 75. 

 Fig. 63. — Cercaria glandulosa; detail of caudal pockets, showing insertion of tail, spinose 



lateral grooves, and three-spined ventral flap. X 100. 

 Figs. 64, 65. — Cercaria glandulosa; outline of excretory vesicle, open and closed. X 200. 

 Fig. 66. — Cercaria glandidosa; genital cell masses, dorsal view. X 110. 

 Fig. 67. — Cercaria glandulosa; sporocyst. X 170. 



