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234 T. B. ROSSETER ON HYMENOLEPIS FRAGILIS. 



embryo is "021 mm. The oval egg is 0*04 mm. in its long axis, 

 and has an equatorial diameter of 0*02 mm. The embryonic 

 hook is 0-003 mm. long. The hook is longer than the root, 

 which in this instance is abnormal. 



Explanation of Plate 18. 



Fig. 1. Sections of strobila, Nos. 1-10, Nos. 1-4 x 70, Nos. 5-8 

 X 35, Nos. 9, 10 x 35. The last two sections are 

 hermaphroditic segments showing position of female 

 and male generative organs. Sec. 9, ventral. Sec. 10, 

 dorsal. V., vagina ; V.C., vaginal canal ; R.S., recepta- 

 culum-seminis ; P.O., D.O., proximal and distal ovaries; 

 S. and Y.G., shell- and yelk-gland ; M.G.P., male genital 

 pore; P.T., D.T., proximal and distal testes; B.G., 

 bursa-geni talium . 



2. Testes with their efferent ducts and vas- deferens ; e.d., 

 efferent ducts; v.d., vas-deferens exterior x 70. 



3. Seminal vesicle filled with spermatozoa dissected from 

 bursa-genitalium ; v.d.i., vas-deferens interior ; R., 

 reservoir of same; V.S., vesicula-seminalis ; c.v.e., coiled 

 vasa-efferentia ; c, cirrus divested of its pouch and 

 sheath x 155. 



4. Prostate gland x 155. 



5. Anterior portion of cirrus-pouch, C.P. ; C, protruded 

 cirrus; C.S., its sheath. 



6. Posterior portion of pouch. 



7. Spinous bulb from cuticle. Fig. 7a. Ring-collar of 

 same divested of spines x 155. 



8. Female organs. V., vagina; V.C., vaginal canal ; R.S., 

 receptaculum-seminis ; f.c, efferent fructifying canal 



x 155. 



9. (a) Ovarian eggs ; (b) early stage of same x 350. 



10. Uterine egg, or six-hooked brood x 350. 



11. One of the six embryonic hooks; a-b, anterior; b-c, 

 posterior x 1,400. 



12. Spermatozoon with spatulate head — diagrammatic. 



13. Hook from scolex of Taenia fray His, after Krabbe x 920. 



14. Hook from scolex of Taenia fasciata, after Krabbe X 920. 



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Journ. Quekett Microscopical Club, Ser. 2, Vol. X., No. 62, April 1908. 



