582 OLIGOCHAETA 



genera it is not known whether the integumental sense-bodies are or are not present : 

 in Preussia the structure of the calciferous gland has only been described in FrattMta 

 lundaensis, which MICHAELSEN only doubtfully refers to the genus; they are stated 

 by him to be like those of Polytoreutus coeruleus. In Preussia siphonochaeta the 

 existence of a pair of calciferous glands in segment xii is rather doubtfully affirmed. 

 The query, however, appears to refer not to the existence of the glands so much as 

 to their function ; for MICHAELSEN discovered no calcareous particles in them. The 

 position of Preussia remains doubtful on account of the absence in MICHAELSEN'S 

 papers upon the two species of this genus of any mention of the presence or absence 

 of the dilated sac upon the sperm-duct, which he terms ' Eiweisskapseln.' The funnels 

 in Preussia siphonochaeta are said to be very large and to occupy nearly the whole 

 of the space within the sperm-sacs ; this suggests rather that the funnels are more 

 like those of such a genus as Stuhlmannia than Polytoreutus, where the funnels 

 are small. In Preussia lundaensis the male efferent apparatus was not developed. 

 All these genera with the exception of Eudrilus furthermore agree in the arrangement 

 of the setae ; in all, with the exception noted, the lateral setae are much closer 

 together than the two setae of the ventral pair. The remaining genera of the 

 family agree, with one exception to be referred to presently, in the following 

 characters - largely the negatives of the characters which distinguish the first group ; 

 they are these : 



(1) Integument without the peculiar sense organs (except in EudrUoides 

 durbanensis). 



(2) The sperm-ducts show no dilatation. 



(3) Calciferous glands, either absent or, if present, consist of a large series 



of paired organs different in structure from those of other Eudrilidae. 



(4) Nephridiopores on each segment generally numerous. 



The genera which certainly show these characters are Stuhlmannia, Nemertodrilus, 

 LibyodrUus, Pareudrilus, and EudrUoides, with the sole exception of EudrUoides 

 durbanensis; this species has the integumental sense organs, but agrees with this 

 second group in the remaining characters. In addition to these Platydrilus, 

 Metadrilus, Megachaeta, Reithrodrilus, Notykus, seem to have no dilatations upon 

 the sperm-duct and no calciferous glands ; but we have no information as to the 

 other character. It is possible that the above statement is not quite accurate ; for 

 MICHAELSEN has recorded in Megachaeta tenuis a series of peculiar organs like 

 fat-bodies along the sides of the gut. These seem to extend as far as the twentieth 

 segment ; it is very possible that they correspond to the structures described by 

 myself in Stuhlmannia and EudrUoides (see below). As regards character No. 4 



