DESCRIPTIONS OF GENERA AND SPECIES 



451 



It will be noted from the above table that all these species agree in a number 

 of important characters ; they have all lobate spermiducal glands, diffuse nephridia, 

 more than one gizzard, a clitellum of about the same extent, and two pairs of 

 spermathecae ; D. sylvuticus, and Periasogaster are peculiar in the spiral intestine ; 

 as, however, this peculiarity also occurs in Plagiochaeta, it is perhaps to be regarded 

 as of less weight for systematic purposes in the present group. Penial setae are 

 either present or absent ; but their presence or absence does not appear to coincide 

 with other differences. Considering that all these species are confined to Australia, 

 it seems hardly necessary to separate them, as FLETCHER has done, into so many 

 as three genera. I may be blamed for allowing them collectively generic distinction 

 from Cryptodrilus, with which they agree in the lobate spermiducal glands and 

 diffuse nephridia ; as it is, I propose to place them all in one genus, which will, 

 therefore, retain the name of Digaster. This genus will be distinguished from 

 Cryptodrilus by the presence of two or three gizzards ; this is the only positive 

 difference. 



MICHAELSEN (13, iv) has proposed to create a genus Fletcherodrilus for FLETCHER'S 

 C. unicus; in the same species he places FLETCHER'S C. fasciatus, and his own 

 C. purpureus, and C. pelewensis, considering them to be nothing more than varieties. 

 The ' genus ' is thus defined by MICHAELSEN : ' Borsten in 8 weit getrennten Reihen ; 

 Offnung der Prostatadriisen (auf dem 18. Segment gelegen) median und unpaarig; 

 ebenso die Offnungen der Samentaschen ; Giirtel nicht iiber die Offnung der Prosta- 

 tadriisen nach hinten hinausragend, ringformig geschlossen ; Darin mit einem einzigen 

 Muskelmagen vor und mit Kalkdriisen hinter den Hodensegmenten ; je ein Paar 

 grosser Segmentalorgane in den einzelnen Seginenten (ausmiindend in den Borsten- 

 linien iv) ; Lagerung der Geschlechtsorgane normal ; ein Paar schlauchfdrmiger Pro- 

 statadriisen (im 1 8. Segment); Penialborsten nicht vorhanden.' 



