some Parasitic Nematodes 499 
than the posterior ; and in addition to these there appears to 
be a subdorsal pair at the extremity of the tail. There are 
at least thirty-three pairs of preanal papillee, arranged in a 
close series on either side of the ventral surface. These have 
rounded granular pulps, and are easily observed. 
In the female the tail measures about 0°5 mm. in length. 
The vulva is situated at, roughly, the anterior third of the 
body—at 50 mm. from the anterior end ina specimen 155 mm. 
long, and at 30 mm. in a specimen 113 mm. long. The 
vagina, in the 113 mm. specimen, runs forward for about 
6 mm., then bends sharply back upon itself and widens 
rapidly into the unpaired portion of the uterus. This runs 
back for a distance of about 12 mm. from the bend before 
giving off the two uterine branches. Each of these, just 
before its junction with the unpaired portion, has a slight 
spindle-shaped swelling. ‘The branches of the uterus merely 
follow a somewhat sinuous course for the greater part of their 
length, but posteriorly they form one or two anteriorly-directed 
loops. They pass into the oviducts at about 26 mm. from 
the posterior end of the worm, The ovarian tubes are slender 
and greatly convoluted, their coils extending posteriorly 
almost to the extremity of the body, and anteriorly to within 
22 mm. of the head-end. Their terminal portions are 
posterior. 
The eggs are roundish-oval, with a thick shell having a 
granular surface-pattern and measuring 0:07—0°875 x 0 065- 
0°07 mm. Many of them contain a fully-formed embryo, 
but others taken from the unpaired portion of the uterus 
show only segmentation-stages. 
IIJ.—Note on T'wo SPECIES OF Porrocacum FROM BIRDS 
[ P. ensicaudatum (Geder, 1800) and P. semiteres (Zeder, 
1800) ]. 
In a previous paper [Baylis (1920)] the writer gave a 
provisional list of species to be assigned to this genus, and 
indicated P. ensicaudatum and P. semiteres as distinct forms. 
The material available for the study of P. semiteres was very 
scanty at the time; but an opportunity having recently 
oceurred, through the kindness of my friend Capt. R. 
Daubney, of examining new and well-preserved specimens 
from Vancllus vanellus, it seems desirable to give a brief note 
on the species. ‘The opportunity has also been taken of 
comparing it with P. ensicaudatum, since there has been 
some doubt as to whether the two forms were not identical. 
