ILLUSTRATION. 



Explanation of plate. Figures 1 and 2 were drawn from mounted specimens 

 stained with hydrochloric-acid carmine according to the usual method. Figures 

 3 and 4 were drawn from digested material lightly tinted with carmine. 



The drawings were made by Hospital Apprentice L. Avery, United States Navy. 



Plate I. 



Fig. 1. Sexually mature segrment showing the genital organs. X about 40. c.= 

 cirrus; c. p.— cirrus pouch; d. c.=dorsal excretory canal; g. p.rrgenital 

 pore; 1. n.=lateral nerve; ov.=ovaries; t.=testicles; trs. c— transverse 

 excretory canal; v. c.=ventral excretory canal; v. d.=:vas deferens; 

 vag.=vagina; y. g.rryolk gland. 



2. Terminal gravid segment, showing egg-balls containing one, two, and three 



eggs. X about 35. 



3. Egg-ball from digested segment, showing outer and inner layers, cal- 



careous corpuscles, and two eggs with their double envelopes. X about 

 180. 



4. Isolated egg from digested egg-ball, showing elongated inner shell con- 



taining six-hooked onchosphere. X about 600. 



175 



