586 OLIGOCHAETA 



size is present in the Geoscolicidae, the sperm-duct opens on to the exterior through 

 it; this appears to be the case, for example, with Geoscolex itself and with Kynotus. 

 The minute structure of the gland in Geoscolex is not known; but it has been 

 described (unfortunately without figures) by ROSA in Kynotus mickaelsenii. The 

 same kind of apparatus exists in K. madagascariensis also (MICHAELSEN, 10). In 

 both the homologue of the ' prostate ' ends in a Bursa propulsatoria. ROSA showed 

 that the sperm-duct penetrated the wall of the bursa, and then ran within the walls 

 of the glandular appendix (the 'prostate') opening into the lumen of the latter. 

 This is almost exactly what is found in the Eudrilidae ; there is a bursa into which 

 opens the spermiducal gland proper (or glands) ; the sperm-duct or ducts open into 

 the lumen of the latter. The fact that in Kynotus the epithelium lining the 

 glandular appendix, or, as I prefer to call it, the spermiducal gland, is composed of 

 two layers of cells renders a comparison with the corresponding structures of the 

 Eudrilidae, lined as they are with a double layer of cells, obvious. On the whole, 

 therefore, it appears that the terminal apparatus of the male ducts in the Eudrilidae 

 is more like that of the Geoscolicidae, than it is like that of the Megascolicidae. 

 The second point in the list of characters of the Eudrilidae which they share with 

 some other worms is the presence of penes ; these organs are not protrusible 

 structures like, for example, the penis of certain Perichaetidae which are simply 

 everted ducts ; the only worms in which anything of the kind exists are the Lumbri- 

 culidae (Stylodrilus and Alluroides only), and, again, the Geoscolicidae ; the genus of 

 Geoscolicidae which shows this character is Siphonogaster ; the two penes of that 

 worm are outgrowths of the body-wall and not eversible processes. Another small 

 point of resemblance between the two families is the frequently intersegmental position 

 of the male pores. The gizzards of the genera Heliodrilus, Hyperiodrilus, and Alvania, 

 situated at the end of the oesophagus resemble so far those of the Geoscolicid 

 Bilimba ; but as exactly the same thing is seen in Pleionogaster, this character is 

 evidently not of so much weight. Of more weight is the position of the spermathoca 

 in many Eudrilids in the neighbourhood of the ovaries; the only other Oligochaeta 

 in which this occurs besides the Geoscolicidae (in which it is fairly common in the 

 subfamily Microchaetidae), are the Lumbriculidae ; the resemblance of this latter 

 family to others is, however, treated of on a subsequent page. As a final point of 

 resemblance, may be mentioned, the elongated sperm-sacs of Polytoreutus to be 

 compared with those of certain Geoscolicidae. The extreme tenuity of these sacs 

 in Polytoreutus finni is to be specially compared with the very slender sacs of 

 Trichochaeta. 



On the whole, therefore, as it appears to me, the nearest allies of the Eudrilidae 



