12 
considerable size, is able to expand the body locally; this holds good 
for both sexes. Probably the cuticle is most finely striated, but it 
has proved impossible to ascertain this, even with immersion lens; 
as, however, the closely related forms usually have a striated cu¬ 
ticle, it is reasonable to presume that this is also the case in this 
species. 
The head is provided with a single ring of rather long brist¬ 
les sublaterally arranged, four in all; they are inserted at the level 
of the front-edge of the large lateral organ just as in the very 
closely related European species P. vulgaris, described by de Man 
in 1907. On the body I have vainly searched for spread hairs. 
In the male are seen three rather stout setæ on the tip of 
the tail and one caudad to the ano-genital aperture (Fig. 8). The lateral 
organ is spirated; it is of different size in the male and the female, 
a feature evidently not uncommon among freeliving Nematodes. 
While in the male the diameter of the spiral makes c. 10 p, it 
only measures 4—5 p in the females. Moreover it is very indis- 
tinct in the females and often very difficult to observe. For the 
same reason my measurements of this organ do not claim to be 
fully correct. 
The buccal cavity is very small and cup-shaped as in the other 
species of this genus; it seems to be devoid of a tooth. The æso- 
phagus is of equal width in its distal part; caudad to the nerve 
ring it increases slightly, and at its base an inconspicuous dilata¬ 
tion is seen. The nerve ring is situated somewhat behind the 
middle of the oesophagus, and a short distance caudad to the nerve 
ring the excretory tube is opening; it is issuing from a rather large 
ampulla. The ventral giand is situated behind the oesophagus and 
is pear-shaped. The duet is very short,- and the ampulla not mueh 
smaller than the giand itself (fig. 5). The caudal giands are pre- 
sumably cephalad to the anal opening as in some other Nematode 
genera e. g. Symplocostoma ; in some of the specimens I have in 
the body cavity observed three globular cells (?) which I consider 
to be the above named giands. 
The vulva is situated in about the middle of the body; it is 
rather inconspicuous and often difficult to see; it is as a rule to 
be found by means of the two coarsely granulated vaginal giands 
which are easily perceived. The ovaries are symmetrical, but their 
