224 P. W. GAMBLE, B.SC. 



materially altered owing to Bohmig's researches. It now reads thus 

 (Bohmig, 57, p. 469): 



Plagiostomidce with a ciliated " circular groove." The oral and genital 

 apertures combined. A germ-yolk-gland present. Spermotheca present, 

 connected with the ovigerous cell-mass (" Keimlager"). 



Genus 21. — Cylindrostoma, Oersted (21). 



The limits of this genus are not yet satisfactorily denned, v. Graff 

 divided it into prosoporous and opisthoporous forms, according as the 

 mouth was anterior or posterior. The latter have been excluded by 

 Bohmig in his definition of the genus, v. Graff's original extension 

 of the genus is, however, here adopted, pending a thorough examination 

 of the Opistoporia. 



48. Cylindrostoma quadrioculatum (Leuckart, 23). 



Length '5 — - 8 mm. Body colourless, somewhat depressed, rounded 

 in front, tapering posteriorly to a long " tail " beset with adhesive 

 cells. Mucus-rods (" Schleim-stabschen "), of an irregular granular 

 character, occur in the epidermis. Flagella are interspersed among 

 the cilia in front and behind. At the level of the brain a pair of well- 

 marked ciliated furrows are present. Mouth ventral, in front of the 

 brain. Pharynx elongate cylindrical, extending from the brain to the 

 centre of the body ; its anterior margin is crenulate, and provided 

 with stout flagella. Brain almost cubical. The genital aperture is 

 combined with the mouth. This remarkable discovery, made by 

 Bohmig, corrects former mistakes due to misleading compression 

 preparations. The testes form large follicular masses surrounding the 

 brain. The different stages in the development of the spermotozoa 

 can be well observed. Behind the penis are a pair of short, wide vasa 

 deferenlia, which open into a highly glandular vesicula seminalis. 

 The penis is a muscular, cup-shaped organ receiving both spermatozoa 

 and granule-secretions from the vesicula, which it transmits through 

 the genital atrium (underneath the pharynx), and so to the exterior. 

 The spermatozoa are elongate, wider in front than behind. The 

 central axis of the tale is markedly granular, and is continued forwards 

 as a spiral thread, wound three times round the surface of the " head." 





