OLIGOCHATA OF TROPICAL EASTERN AFRICA. 251 
While we may, as it appears to me, term Moniligaster an 
earthworm with numerous points of affinity to the “ water- 
worms,” it is better to speak of Alluroides as a “water- 
worm”? with affinities to the terrestrial worms. If an exchange 
could be effected between these two genera of various characters, 
we should get as a result either an obviously terrestrial genus 
or an equally obviously “ Limicoline” genus. Thus Allu- 
roides would be undoubtedly referable to the terrestrial sec- 
tion of the Oligocheta if it possessed the body-wall and the 
ova of Moniligaster; on the other hand, Moniligaster 
would be an undoubted “waterworm” if we could transfer to 
it the body-wall and the ova of Alluroides. 
It is therefore, in my opinion, useless to attempt any 
comparison with any particular family of terrestrial Oligo- 
cheta; it is rather with some family of the aquatic Oligocheta 
that Alluroides should be compared; be it noticed, however, 
that, judged by external characters only, Alluroides would 
probably be referred to the immediate neighbourhood of 
Allurus. 
The family of “ waterworms” with which Alluroides has 
the closest affinities is that of the Lumbriculide. It agrees 
with that family in the following characters : 
(1) Setze paired and S-shaped. 
(2) Atrium with thick peritoneal investment.! 
(3) The great depth of the single layer of longitudinal 
muscular fibres. 
These two characters are found together in the Lumbriculide 
alone among the aquatic Oligochzeta; in other respects, however, 
there are not any striking resemblances between the genus 
Alluroides and the Lumbriculide. 
Two of the most characteristic features of this family are 
wanting in Alluroides; these are (1) the absence (?) of the 
vascular contractile ceca, and (2) the absence of a second pair 
1 T have shown that in Moniligaster the cells enveloping the atrium are 
prolonged through the muscular layer and epithelium to open into its lumen; 
Vejdovsky’s figure (‘ Zeitsch. wiss. Zool.,’ Bd. xxvii, pl. xxiv, fig. 3) seems to 
show that this is also the case with Rhynchelmis. 
