444 OLIGOCHAETA 



The Cryptodrilidae includes the following genera : — 



(x) Digaster, Peeeiee. (9) Microscolex, EosA. 



(2) Pontodrilus, Pekeiee. (10) Nannodrilus, BeDDARD. 



(3) Plutellus, Peeriee. (xi) Ocnerodrilus, ErsEN. 



(4) Typhaeus, Beddaed. (13) Gordiodrilus, Beddaed. 



(5) Megascolides, McCoY ( = M"oto- (13) Microdrilus, Beddaed. 



seolex, Fletchee). (14) PletelierodrilTis, Michaelsen. 



(6) Cryptodrilus, Fletcher. (15) Trinephrus, Beddaed. 



(7) Diehogaster, Beddaej>. (16} MiUsonia, Beddaed. 



(8) Deodrilus, Beddaed. 



This list includes all the genera which are accepted in the present work. A few other names have 

 been given, i. e. Notoscolex, Didymogaster, Deltania, Perissogaster, Argilophilus, Ehododrilus, and Phoiodrilits, 

 which I regard as synonymous with some one or other of the above. 



The Crj'ptodrilidae are, like many other families of terrestrial Oligochaeta, of 

 various sizes ; at the one end of the series we have the ' Giant earthworm of 

 Gippsland,' which is one of the largest of its kind ; at the other extreme there 

 are the tiny species of Gordiodrilus and of the genera Microdrilus and Microscolex. 



With the exception only of the genus Deodrilus, all the Cryptodrilidae have 

 a prostomium, ; in no Cryptodrilid are there more than eight setae in each segment; 

 these setae may be strictly paired, or they may be in many species, disposed in eight 

 equidistant lines ; Spencee (2) has described an irregular arrangement of the setae in 

 certain Australian members of the genera Cryptodrilus and Megascolides, limited to 

 the posterior segments of the body. In two genera only have ornamented setae 

 so characteristic of the family Geoscolicidae been met with ; I described in Deodrilus 

 jachsoni setae of this kind, and, more recently, Michaelsen has found ornamented 

 setae in Pontodrilus bermudensis. The setae of Deodrilus are defective upon the 

 first five segments of the body ; this peculiarity, so common among the Geoscolicidae, 

 is not, to my knowledge, found elsewhere among the Cryptodrilidae (unless possibly 

 in MiUsonia). Nor do we meet with any special modification of the clitellar setae 

 such as is even more common among the members of the last-named family. The 

 setae are, as in many other worms, occasionally defective upon the segment which 

 bears the male pores ; this is the case, for example, with Diehogaster, where the ventral 

 setae of the seventeenth segment are totally absent. 



Dorscd pores are present or absent. The clitellum is of variable extent ; it does 

 not commence before the twelfth segment, and may extend back as far as the twenty- 

 second ; no Cryptodrilid has a clitellum consisting of fewer than three segments and 



