DESCRIPTIONS OF GENERA AND SPECIES 585 



(a) The degenerate calciferous glands in certain forms and the unpaired 

 pouches of others. 



(3) The integumental nephridial network of Libyodrilus, &c. 



(4) The presence of a single spermatheca placed in the neighbourhood of the 



ovaries. 



(5) The presence of coelomic pouches functioning as spermathecae in many 



forms, and in others enclosing the ovaries. 



(6) The sometimes dilated extremity of the sperm-duct, and the position of 



the funnels with reference to the septa. 



The above structural features are absolutely confined to the Eudrilidae in the 

 form in which they occur; Nos. 2, 3, 4, however, are only partially distinctive. 

 My genus Gordiodrilus has a single pair (for one only) of ventral pouches, whose 

 structure is not unlike the modified calciferous glands of such a form as Stuhlmannia 

 (see p. 62). In Acanthodrilus, and possibly in other worms with a diffuse nephridial 

 system, the tubes branch within the body-wall, but this is never correlated with 

 paired nephridia as it is in the Eudrilidae. The position of the spermathecae in the 

 vicinity of the ovaries is also found in many Geoscolicidae. A few other characters 

 of the Eudrilidae are not so restricted to that group, although very characteristic ; 

 they are : 



(1) The opening of the sperm-ducts into its glandular appendage. 



(2) The existence of a penis (or penes) which are permanent processes of the 



body-wall. 



(3) The generally unpaired generative orifices. 



(4) The presence of a number of gizzards at the junction of the oesophagus 



with the intestine. 



The above characters occur in several species ; besides these there are a few 

 other characters which are each confined to a single genus or species, and which 

 are rarely met with elsewhere. Such are : 



(1) The spermatophores of Polytoreutus. 



(2) The peculiar glands appended to the base of the spermatheca of certain 



species of Eudriloides and Notykus. 



(3) The disappearance of the ovary in mature forms (Libyodrilus, &c.). 



(4) The ciliation of the spermiducal gland in Eudriloides, &c. 



The opening of the sperm-ducts into the spermiducal gland is a character which 

 is shared by the Eudrilidae with practically all the lower Oligochaeta, and with the 

 Moniligastridae among those families placed by ROSA and by others in the group 

 Terricolae. It is noticeable, however, that when a similar gland always reduced in 



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