[ 39 ] 

 THE HARTHWORMvS OF IRiaAND. 



BY REV. HII.DERIC FRIEND, l-M^.S. 

 (Continued from page lo.) 



The genus AUoIohophora is represented in Great Britain by 

 some fifteen species. I vSliall, however, treat half-a-do/cn of 

 them under the more expressive and accurate designation of 

 De7idrobccna, or tree-worms, thus leaving about half-a-score 

 for discussion under this head. So large a group is certain to 

 present a considerable variety of forms, and by a systematic 

 study of each species it is possible to separate the genus into 

 two or three well-marked groups, thus enabling the student 

 the more readily to identify the various forms. Before we 

 proceed to this subdivision, however, it will be desirable to 

 obtain a clear idea of the genus as a whole. 



It was exactly twenty years ago that Bisen, after a ver}^ ex- 

 haustive study of the worms of Scandinavia, decided to split 

 up the old genus Lumbricus into three. He retained the earlier 

 name for the genus discussed in the first part of my paper; 

 and adopted two new names for the genera he had separated 

 therefrom. These names, if they lack meaning at first sight, 

 and when studied independently of their histor>^, are found to 

 be very expressive when their origin is recalled. As I have 

 already pointed out, the genus Lumbricus is readily recognised 

 by the complete mortise and tenon arrangement of the head. 

 Some v^orms, however, were seen to have the lip but partially 

 dovetailed into the first segment or prostomium, and they were 

 at once set apart as "the worms with a different head," or in 

 scientific language, Allolobophora. One or two worms again, 

 had not only a different head from that w^hich characterised 

 Lumbricus, they had further a differently shaped tail and differ- 

 ently placed male ^ox^^ixom.ho'C^LiLinbricus^iwCiAUolobophora, 

 and so merited the name of " the worms with a different tail " 

 or A Hums. The genus Dendrobcena was an afterthought, and 

 the name was invented to express the fact that the worms so 

 named inhabited decayed trees and timber. 



Thus, while the genus Allolobophora agrees with Allurus in 

 the manner in which the lip is inserted or imbedded in the 

 first ring, it differs from that genus in the shape of the tail 

 and the position of the male pores. Again, wdiile some of the 



