94 



ZOOLOGY 



system. Hermaphrodite; follicular testis and paired 

 ovaries. Marine. Frequently with brown or green 

 parasitic algae. Convoluta, Proporus. 

 Tribe 2. Rhabdocoela. — Stomach distinct from parenchyma, 

 and simple. Pharynx complicated. Compact testes and 

 ovary, the latter divided into a germarium and vitel- 

 lariv/m. Otocysts rare. Marine, freshwater, and land 

 forms. 



Prorhynchus inhabits damp earth. The Meso- 

 STOMIDA andVoETiciDA are the chief freshwater famihes ; 

 the latter includes two parasitic genera — GraffXla found 

 in Gastropods, and Anoplodium in Holothurians. 



Fia. 65. — Plan of an AUoioooelon.^ Turbellarian. 

 After Von Graff. 



1. Bursa copnlatrix. 



2. Brain. 



3. Bye. 



4. Germarium. 



5. Intestine. 



6. Longitudinal nerve trunk. 



7. Mouth. 



8. Pharynx. 



9. Testis. 



10. Yolk gland. 



11. Vesicula seminis. 



12. Oviduct. 



<J . Chitinous copulatory organs. 

 S 9 . Common sexual aperture. 



Tribe 3. Alloiocoela. — Stomach loled or irregular, pharynx 

 present, testes follicular. Otocysts occur in the family 

 Monotida. 



All marine, except Plagiostoma Lemani, which in- 

 habits the deep water of certaia Alpine lakes. 



