219 
den einzelnen Klumpen und an den Wånden des Gefåsses hinziehen; 
andere ballen sich zu Klumpen zusammen, in welchen sich viele 
Hunderte der Thierchen umeinander herumwinden". The description 
Bitschli gives of the behaviour of this species reminds one of 
other Nematodes of putrefaction, for instance Rhabditis and Diplo- 
gaster, which forms it resembles as to the great number of eggs 
which it produces. It is ovoviviparous, a fact that is often observed 
among the Rhabditides, and the body of the female is frequently 
swarming with large young. 
I have found this species both in the Kalkbrænderihavn near 
Copenhagen and at Charlottenlund. And even if I have not seen 
it in such lots as Bitschli describes, my opinion is that it is 
a rather common littoral-form which will appear in putrefying sea- 
weed and which probably can be found all round our coasts. 
Monohystera crassissima n. sp. 
Pl. III. Figs. 14, 15, 22. 
I found the species for the first time in July 1909 among 
Conferves from a pool on the meadow near Øresund by Hellerup. 
As the material had been standing for a few days in a Petri-cup 
and began to putrefy I remarked that the individuals of the Nema- 
todes increased conspicuously in number and after some days more 
I had a regular culture. This only kept for a while; when the 
putrefaction augmented the animals died rather speedily. Later I 
have taken the species several times at the same locality but al- 
ways only single individuals and I have not succeeded in my 
attempts at getting a culture anew. I suppose that we here have 
to do with a typical Nematode of putrefaction like MM. socialis 
Biitschli, the single specimens I have met with later on being young, 
immature individuals roamingabout. 
The shape of this species is extraordinarily clumsy but it is 
very agile and has some resemblance to diminutive fly-maggots, 
which is particularly striking where it is found in abundance. It 
has its average width about the middle of body and is tapering at 
