484 OLIGOCHAETA 



XVI. Last pair of hearts in XII. Sperm-sacs in IX, XII ; spermathecae in VIII, IX, 

 with a single diverticulum. Hob. Near Paramatta, Sydney. 



(4) Trinephrus dubius (SPENCER). 

 Cryptodrilus dubius, SPENCER, P. R. Soc. Viet., 1891, p. 136. 



Definition. Length, 'three and a half inches'; diameter, 'less than a quarter inch.' 

 Prostomium complete. Setae of outer couple further apart than of inner. Male pores 

 ventral of level of setae 2. Paired papillae on XVII, median papilla on XVIf/XVIII. 

 Dorsal pores commence V/VI. Gizzard in V; calciferous glands in XV, XVI ; intestine 

 begins in XVIII. Sperm-sacs in XI, XII ; spermathecae in VIII, IX, with two diverticula. 

 Spermiducal glands two pairs as in T. fastigatus. Hob. Victoria. 

 SPENCER remarks that this species is to be distinguished from T. fastigatus by 



the possession of well-developed calciferous glands and by the sperm-sac not being 



racemose ; the two are evidently very closely allied. 



Genus DIGASTER, PERRIER. 



Syn. Perissogaster, FLETCHER. 

 Didymogaster, FLETCHER. 



DEFINITION. Prostomium incompletely divides buccal ring. Clitellum, XIII 

 (XIV)-XVII (XVIII). Gizzards, two or three. Nephridia difluse. Spermi- 

 ducal glands lobate. 



I have already given my reasons for associating the three genera Digaster, Perisso- 

 gaster, and Didymogaster into one genus, which must obviously be called Digaster. 

 As thus constituted the genus will contain seven species. It is, as I have already 

 indicated, very close to CryptodrilvA. 



The most remarkable species in the genus is perhaps D. sylvaticus, with its spirally- 

 arranged intestine ; this character is, however, found elsewhere among the terricilous 

 Oligochaeta, for it has been described by BENHAM in Plagiochaeta. There are two 

 other genera of Cryptodrilids nearly allied to the present which possess two gizzards ; 

 these are Dichogaster and Microdrilus; but the present genus differs from both of 

 these in having the male pores upon the eighteenth segment instead of the seventeenth. 

 The two genera mentioned have also tubular spermiducal glands. On these grounds 

 chiefly, though there are also minor points of difference, I distinguish both of them 

 from each other and from Digaster. The type species of Digaster is D. lumbricoides. 



