EXPLANATION OF THE PLATES. 417 



Fig. 15, c. Length of claw. 



d. Total length of the lateral process, (spine, Dora, Tap). 



e. Breadth of the same. 



f. Breadth of stalk. 



i. Hooks (first and second rows) of Tcenia serrata and Cysticercus pisiformis. 



ii. Ditto of Tcenia ex Cysticerco tenuicolli and of Cysticercus tenuicollis. 



in. Ditto of Tcenia solium and of Cysticercus celhdosce. 



iv. Ditto of T. litterata, Rudolphi, and of Cysticercus. 



v. Ditto of T. crassiceps, Dujardin, and of Cysticercus. 



vi. Ditto of T. crassiceps, Rudolphi, and of Cysticercus. 



vn. Ditto of T. intermedia and of Cysticercus. 



vm. Ditto of Echinococcus scolicipariens. 



ix. Ditto of E. altricipariens. 



PLATE (TAB.) V. 



1. Distoma hepaticum, with the ramifications of the intestinal tube, twice natural 



size. 



2. The same magnified twenty times. 



a. Oral sucker. 



a', a'. Cut ends of the intestinal tube. 



b, b, b, b. Yelk-sacs which collect together in the lateral ducts, b', V , which 



communicate with a lenticular enlargement c', by a transverse branch 

 from each side, c. The convoluted uterine duct, d, d, d, proceeds from c', 

 becoming larger as it proceeds, and terminates in the narrow vagina, e, e. 

 f. The ventral sucker. 

 y, g, g. Convolutions of the testes. 



h. The germ-stock lying behind c. Continuation of g, representing a vesicula 

 seminalis interna, appearing to open into h', the commencement of the 

 uterus. 

 i, i. Funiculi spermatid proceeding from a tube k at the entrance of the sac 

 of the penis, which is seen to communicate with the male organ of gene- 

 ration. 



The red lines indicate the organ of excretion which forms behind a 

 large efferent vessel which in the young Distoma is seen to contain 

 small transparent globules. The connection between this organ and 

 the vascular system has not been clearly made out. 



3. The parts c' and h of the foregoing figure magnified. 



a. Point of union of the yelk-sac. 



b. Germ-stock (ovary). 



c. Single yelk-cells (vitelline bodies), as they pass from a. 

 4 — 6. Eggs of the Distoma in various stages of development. 



7. Tip of the penis magnified. 



8. Portion of the spinous membrane (magnified 500 times). 



9. Development of the spermatozoa. 



10. Peculiar vacuoles formed by muscular layers. 



11. Distoma lanceolatum. 



a. Oral sucker, oesophagus, and blind double intestinal tube. 



