SOME RECENT MEMOIRS UPON 0L1G0CHJETA. 197 



and myself. The matter requires renewed investigation. 

 In any case Bourne, Vejdovsky and I have shown that the 

 " plectonephric " condition, as Benham has termed these 

 diffuse nephridial tubes, is preceded by a series of paired 

 nephridia one pair to each segment. This has been proved 

 in Pericktzta, Qciochcetus and Megascolides. The nephridium 

 elongates and becomes thrown into loops, each loop finally 

 appears in Megascolides to break away and to form a 

 distinct and separate nephridium. It is clear, therefore, 

 that whether or not the connection is retained in Octochcetris 

 and Perichceta there is originally a connection, so that that 

 matter is of less importance than the alleged intercom- 

 munication from segment to segment. This multiple 

 arrangement of the nephridia is only found in the families 

 Acanthodrilidae, Perichsetidae and Cryptodrilidae, and is the 

 principal argument for uniting them into one superfamily, 

 Megascolicides, as I have done in my Monograph. Brachy- 

 drihts, however, is a member of the family Geoscolicidse, 

 but it has only two pairs of nephridia to each segment ; 

 there is nothing like the complicated system of Perichceta. 

 This family Geoscolicidse has been through the recent re- 

 searches of Rosa and Michaelsen brought still nearer to the 

 Lumbricidse. It was always difficult to separate them, 

 mainly on account of the aquatic Criodrilus, now it is 

 practically impossible unless we accept Michaelsen's inter- 

 mediate family Criodrilidse. The ornament setae which 

 used to be a distinctive mark of the Geoscolicidse have 

 been found by Michaelsen in Allolobophora moebii and 

 in A. lonnbergi ; many Geoscolicidae, e.g., Microckceta are 

 distinguished by the fact that instead of a single pair 

 of spermathecae in each of those segments which con- 

 tain them there are a considerable number of minute 

 pouches ; this distinction, however, falls to the ground 

 since more than one Allolobophora is now known to 

 possess the same character — which has moreover been met 

 with in Perichceta. It is in these two families that most 

 instances are met with of total absence of spermathecae ; 

 Kynotus, a Madagascar genus, is anteclitellian like the 

 Lumbricidae, and in short it seems impossible to lay down any 



