DESCRIPTIONS OF GENERA AND SPECIES 371 



I allow 39 species as sufficiently defined ; in addition to these there are a few 

 others which have not been, as yet, adequately described ; these are contained in 

 BOURNE'S preliminary list of Indian earthworms. 



He describes five species which appear to me to be referable to Megascolex ; these are P. biraginata, 

 P. latcsoni, P. gracilis, P. hulikalensis, and P. salettensis. Of these P. salettensis and P. bivaginata 

 are probably identical with my M. armatus. I am informed by BOURNE that this is the case. 

 I refer P. lawsoni to the genus on account of the fact that it has a clitellum extending over four 

 segments, no intestinal caeca, gizzard in vi, penial setae, and, finally, since the ordinary setae 

 are absent between the male pores. P. gracilis is, in my opinion, a Megascolex, for some, though not 

 all, of the same reasons : it has an extensive clitellum, paired oviducal pores, no setae between 

 male pores, and a gizzard in segment v. It is not, however, possible to regard the species as 

 fully established in the light of our present knowledge of the species which belong to this genus ; 

 at the time when this preliminary account was published, FLETCHER'S series of papers upon Australian 

 earthworms was not complete ; hence certain characters requisite to define these forms, and to separate 

 them from some of those described by FLETCHER are not given by BOURNE. 



Several species belonging to the genus, which I extend for their inclusion, have 

 only eight setae on the first few segments. The same character occurs in some species 

 of the genus Diporochaeta. 



Three species, viz. M. margaritaceus, M. iris, and M. pictus, form a group which is 

 really intermediate between Perichaeta and Megascolex, as will be seen from the 

 descriptions of these species which follow. It is very doubtful indeed whether they 

 are rightly assigned to the present genus. The principal reason which leads me to 

 place them therein is the extensive clitellum and the dorsal gap in the line of setae. 

 Other intermediate forms are to be found among the Australian species described 

 by FLETCHER and SPENCER. Thus M. indissimilis has its clitellum limited to 

 segments xiv-xvi ; so too has M. australis. The occasional presence of only one 

 instead of two oviducal pores is, perhaps, rather to be looked upon as evidfcnce of the 

 close relationship of the genera Megascolex and Perichaeta, than to be made much of 

 to emphasize the 'intermediate' character of any particular species. 



In the following description of species it must be also understood that the gizzard 

 occupies the fifth segment unless it is otherwise stated, and that the spermathecae have 

 a single diverticulum. 



For convenience in identification the species may be roughly classified thus : 



Spermathecae in vii-ix . M. stirlingi 



M. canaliculatua 



sperm-sacs in xi, xii. 



M. gracilis 



M. iris ) 



\ gizzard m viu-ix. 

 M. margantaceu* j 



3 n 2 



