194 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Structure of the Oligochaeta.* — Mr. F. E. Beddard, referring to 
Dr. W. B. Benham’s division of the Lumbricomorpha into Microdrili 
and Megadrili, points out that the presence or absence of a capillary 
network upon the nephridia is not the only character by which these 
two orders might be distinguished. There are in addition — 
Microdrili. 
(1) Sexual maturity at a fixed 
period. 
(2) Clitellum consisting of a single 
layer of modified cells only. 
(3) Ova large and few. 
Megadrili. 
(1) Sexual maturity more or less 
continuous. 
(2) Clitellum consisting of two 
distinct layers of cells. 
(3) Ova small and numerous. 
Ocnerodrilus , however, presents such an admixture of these characters 
that the proposed division seems almost impossible. Mr. Beddard is 
inclined for the present to revert to Vejdovsky’s arrangement into 
families only, and he points out that, in discussing the affinities of any 
particular type of Oligochaeta, it is necessary to compare it with a 
particular family. 
Pelodrilus is the name proposed for a new generic type of Annelid 
collected, in New Zealand, from wet soil near the margin of a swamp. 
Among other points of interest this new worm has specially thickened 
intersegmental septa in some of the anterior segments ; this tends to 
show that the medium in which the worm lives has some relation to the 
presence of these thick septa ; for it does not, like its immediate allies, 
swim in water or burrow in naturally soft mud. 
Phreodrilus is another new New Zealand worm in which the general 
arrangement of the sperm-duct is quite unique, unless it resembles that 
of Eclipidrilus. The atrium commences as a sinuous tube which widens 
out to form a large thin-walled sac with muscular walls ; this sac is 
nearly filled by a much coiled continuation of the atrium and vas deferens. 
This genus has highly characteristic setae ; the dorsal rows consist each 
of a single capilliform seta, not unlike those of the Tubificidae ; the 
ventral setae are not quite similar to those of any known Oligochaete. 
Mr. Beddard concludes with a note on the zone of growth in TJrochseta , 
and a brief description of a new species of Pontodrilus from Bermuda, in 
which the gizzard is very feebly developed. 
Homology between Genital Ducts and Nephridia in Oligochaeta. t 
— Mr. F. E. Beddard has studied the development of Acanthodrilus 
multiporus. In the young embryos each segment is furnished 
with a pair of nephridia, each opening by a ciliated funnel inter- 
nally. Later on, the funnels degenerate and that portion of the tube 
which immediately surrounds the funnel becomes solid. At the same 
time the nephridium branches and communicates with the exterior by 
numerous pores. At a rather early stage four pairs of gonads are 
developed in segments x.-xiii., each on the posterior wall of its 
segment ; the funnels in close contact with them increase greatly in 
size and become the funnels of the vasa deferentia and oviducts ; subse- 
quently the gonads and commencing oviducts of segment xii. atrophy. 
The author can only explain these and other facts which he brings 
* Ann. and Mag. Nat. Hist., vii. (1891) pp. 88-96 (2 figs.), 
f Proc. Koy. Soc., xlviii. (1891) pp. 452-5. 
