192 
Trematodes of Fish 
reservoir on the left of the ovary. A long Laurer’s canal is present, but 
no receptaculum seminis. 
The genital aperture is situated in the middle line immediately in 
front of the ventral sucker. The cirrus-pouch is small and slender. As 
a rule it extends about 014 mm. behind the ventral sucker. It contains 
a small, simple vesicula seminalis, a short pars prostatica and a long 
ductus ejaculatorius. No spines could be detected either in the cirrus 
or in the vagina. The latter is about, the same length as the 
cirrus-pouch and lies to its left side. The uterus is confined to the 
median field and is of short extent. Its initial part is filled with 
spermatozoa and the ova are usually few in number. They measure 
0094 x 0 047 mm., and have the characteristic shape indicated in the 
previous description. 
Family FELLODISTOMIDAE n. nom. 
Steringophoridae Odhner, 1911. 
Odhner’s proposal (1911, p. 98) to change the name Fellodistominae 
to Sievingophorinae has little to justify it. The former name was 
perhaps not the most happy choice and it may readily be admitted 
that as a matter of taste the latter is more apjDropriate. It is surprising, 
however, to find an experienced systematist such as Odhner allowing 
himself to be swayed by such a consideration. It is obvious that the 
name Steringophorinae cannot stand but must give place to the earlier 
Fellodistominae. The name of the family should consequently be 
changed to Fellodistomidae. 
Tergestia laticollis (Rud.). 
Only a single specimen of this parasite was obtained from the 
intestine of the horse-mackerel ( Trachurus trachurus). It is apparently 
not a common parasite in the North Sea, but it is comparatively frequent 
on the south coast. 
An amended description of the species has recently been published 
by Odhner (1911, p. Ill) but the dimensions which he gives for the 
various structures are somewhat misleading. They can only apply to 
specimens of an average size, which, although not stated by Odhner, is 
probably about 2'5 mm. 
In my collection of specimens from the south coast I have found the 
average length to be 2’65 mm. of which the neck comprises exactly 
one-third. The maximum breadth across the ventral sucker is about 
