EISEN 



IMPORTANCE OF THE PENIAL BULB IN CLASSIFICATION. 



The present arrangement of the various genera is partly tentative. 

 Until now the structure of the penial bulb has not been critically 

 examined, except in a few species besides those described in this 

 paper, and it is in reality only a supposition that the structure of the 

 penial bulb is uniform in the respective species of a genus. I think, 

 however, this assumption will prove to be correct. The species within 

 each of the genera which have been examined have proved to corre- 

 spond in all particulars to such an extent that it may be safely assumed 

 that the other species also will agree. 



Of the genera of the family, I have not had any opportunity to 

 examine Bucholzia and Achceta. Of Bucholzia I have not been able 

 to find any description referring to the structure of the penial bulb, 

 and this genus is simply inserted in the subfamily Lumbricillinae on 

 account of its undoubted relationship to the genus Henlea. Chiro- 

 drilus, which has not been seen by any recent investigator of this 

 family, is appended for convenience sake. Of its interior structure 

 we know nothing. 



Structure of the penial bulb. The copulatory cushion or penial 

 bulb is of considerable importance in the classification of Enchytra- 

 ida;, and I have as far as it has been possible investigated its structure 

 in all the species described in this paper. In some instances the pres- 

 ervation of the specimens has not been sufficiently perfect to allow a 

 minute microscopical study of these complicated structures, but these 

 instances have been comparatively few, and it seems almost certain 

 that a great uniformity of structure exists in the different species of 

 the same genus, or in the same genera of the various subfamilies. 

 The structure of the penial bulb or corresponding organs can therefore 

 be said to be highly characteristic of both species, genera and sub- 

 families. As previous investigators have paid little or no attention to 

 the finer structure of these sexual organs I will here refer to them 

 more in detail in order that the following classification may be better 

 comprehended. 



In nearly all species of this family there exist one or several pecu- 

 liar cushions in the vicinity of the spermiducal pore the pore in 

 which opens the sperm-duct leading from the funnel. This cushion or 

 bulb is either intimately connected with the lower part of sperm-duct 

 in such a way that the lower part of the duct is enclosed by the bulb, 

 the spermiducal pore then being situated nearly in the center of the 

 outer surface of the bulb. Or the pore of the sperm-duct may be sit- 



