472 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
confirmed by the difference in colour between the blood of a quite young 
Nephelis and the blood which fills the coelom, for one is red and the other 
yellow. Later on this difference in colour disappears. 
After some notes on the development of the nephridia the author 
treats at greater length of that of the generative organs. He finds that the 
ovaries are developed on the peritoneum of sections of the coelom which, 
later on, become constricted off from it and cease to communicate with it ; 
they then form special ovarial cavities on either side of the ventral 
cavity. The testes commence as a ridge of cells derived from the fusion 
of rudiments which have appeared in each segment on the peritoneum. 
This ridge becomes constricted off for its whole length from the coelom, 
is hollowed out and formed into a tube. This gives rise to the testicular 
sacs by developing numerous outgrowths which widen out more and 
more, but never lose their connection with the genital tube. The 
epithelium of the testicular sacs which is derived from that of the tube, 
and ultimately from the peritoneum, gives rise to the rudiments of the 
male generative cells. The genital tube persists and takes on the 
function of a vas deferens. The development of the organs of the male 
copulatory apparatus is very complicated, but is interesting, from the 
histogenetic point of view, in consequence of the various glandular cells 
and muscular layers which go to make it up. In the course of his investi- 
gation the author was much struck by the many points of resemblance 
between the developmental history of Neplielis and that of certain 
Annelids, so that he is brought to regard the Hirudinea as a special group 
of that division, standing nearest to the Oligochaeta. 
B. Nematlielmintlies. 
Nectonema agile.* — Dr. 0. Burger has made a study of this little- 
known worm, which, with some doubt, Prof. Yerrill, its original describer, 
regarded as a Nematoid. The investigation shows that it is certainly a 
round worm, and it has some points of affinity to Gordius. It resembles 
it in the want of lateral areas, and the developed ventral ridge recalls 
the nervous system of Gordius ; in its muscular and digestive apparatus 
it approaches rather Trichocephalus , but it is peculiar in having only a 
very small part of the enteric wall formed of four cells, and the rest 
consisting of two rows of cells only. In this latter point there is like- 
ness to the Bhabditis- forms, but they have a pharynx which Nectonema 
has not. On the whole, the form seems to occupy a very isolated 
position. 
Anticoma.j — Mr. N. A. Cobb has a monographic account of this 
genus of free-living Nematodes, in which he gives a detailed definition 
of the genus and of its four constituent species, one of which, A. typica , 
is new. 
y. Platyhelminthes. 
Diplozoon nipponicum-l — Mr. Seitaro Goti describes a new species 
of this remarkable Trematode which differs from D. paradoxum in the 
smallness of the posterior suckers, the greater length of the posterior 
* Zool. Jahrb. (Abth. f. Anat.), iv. (1891) pp. 631-52 (l pi.). 
f Proc. Linn. Soc. N.S.W., v. (1891) pp. 765-74 (2 figs.). 
\ Journ. College of Science, Imp. Univ. Japan, iv. (1891) pp. 151-92 (3 pis.). 
