ON MEGASCOLEX CCEEULEUS. 55 



The male pores lie immediately ventrad of the most ventrally 

 placed seta in segment xviii. There are, as stated by Beddard, 

 two other pairs of apertures in this region, though not exactly 

 in the position stated by him. The one pair lies between seg- 

 ments XVII . XVIII, and the other between segments xviii . xix. 

 These pores are the apertures of the glands described below 

 (p. 83). 



All these six apertures lie about equally near the median 

 ventral line and opposite setae 7 (figs. 2 and 13). 



In the living worm there are no papillae and no depressions 

 in this region, but when the worm is killed and contraction of 

 the body-wall takes place a depression is produced, as shown 

 in fig. 13, and the pores lie at the edges of this depression, the 

 male pores upon papillae.^ 



Dorsal Pores. — The most anterior dorsal pore lies between 

 segments vi and vii, and other dorsal pores occur between 

 every two segments, including the clitellar segments.^ 



BODY-CAVITY. 



This is as usual incompletely divided into separate chambers 

 by the septa.^ 



separated chiefly because I believed them to dififer in this respect, are the 

 same species, and, indeed, the same as P. armata. 



' There can be little doubt that the majority of papillae which have been 

 described in the region of the genital apertures of so many earthworms are 

 not permanent structures, but produced by contractions of the body-wall ; 

 they are regions doubtless in which some portion of the muscular layers are 

 absent, so that when general muscular contraction takes place they stand up 

 as papillae ; and when a worm is so killed as to become greatly contracted 

 these papillae are seen, but if the same worm had been gradually killed 

 they would not appear. Great care should consequently be exercised in 

 using such papillae as classificatory characters. 



2 These dorsal pores are important in classification. In some genera they 

 are absent (Eudrilus, Teleudrilus, Thamnodrilus, Moniligaster, &c.). The 

 position of the most anterior pore varies in different species. Sometimes 

 they are absent from between every two clitellar segments. 



* The body-cavity of any segment is ordinarily bounded by two septa. The 

 anterior septum of a segment N may be conveniently termed septum jj — i . n. 



