236 



OLIGOCHAETA 



almost obliterated lumen. None of these genera possess penial setae, which are only- 

 found in Ilyodrilus and Bothrioneuron ; indeed the ventral setae of the eleventh 

 segment, upon which the male pores are situated are altogether absent from the ■ 

 sexually mature worm. It is not altogether easy to compare tho efferent apparatus 

 of the various genera of Tubificidae among themselves. 



Fig. 40. 



Fig. 38. 



MALE EPPEEENT 

 APPAEATUS OF 

 LOPHOCHAETA. 



(After Stole.) 



I. Funnel. 2. Penis. 3. 

 'Atrium.' 4. 'Prostate.' 

 5. Coiled sperm-duct. 



Fig- 39- 



ILYODRILUS COCCINEUS. 



MALE EFFERENT APPARATUS. 



(After Stole.) 



I. Funnel. 2. Sperm-duct. 3. Penis. 

 4. Muscles for its retraction. 5. 



Glandular covering of 6. 'Atrium.' 



BOTHRIONEURON VE.TDOVSKYANUM. 



MALE EFFERENT APPAEATUS. 



(After Stole.) 



I. Proximal region of 'atrium.' 2. ' Para- 

 trium.' 3. Distal region of ' atrium.' 4. Penial 

 setae. 5. External pore. 6. Muscles for pro- 

 trusion of distal end of efferent apparatus. 

 7. Muscle attached to sperm-duct (8). g. Funnel. 



The simplest form is unquestionably that of Ilyodrilus, which leads to the Naids 

 and Lumbriculidae. 



If it were not for Branchiura, the more specialized chamber of Tubifex, &c., 

 might be regarded as produced by further diiferentiation of the simple globular sac 

 of Ilyodrilus, particularly since, as Vejdovsky pointed out, the complex terminal 



