61 
it is circular and armed with cbitinous sickle- shaped hooks from 
twelve to fourteen in number, with their apices directed inwards. 
The ovary is an opaque mass almost at the centre of the body, 
from which runs a curving oviduct leading to a uterus. Like Van 
Beneden I have never seen more than one egg in the latter at a 
time. The egg is pale yellow, with a process at each end. On 
the right side of the ovary is a smaller mass— the testis according 
to Van Beneden— but I have not been able to follow the related 
parts. The vitellaria are much developed and occupy almost the 
whole of the body, even running into the posterior processes. A 
conspicuous longitudinal vitellarian duct runs down each side of 
the body, and a transverse duct from each side joins near the 
middle to open into the oviduct. 
Genus— Pterocotyle (v. Ben. and Hesse). 
Pterocotyle palmata (Leuckart). (Plate V., fig. 3.). Van 
Beneden and Hesse, " Becherches sur les Bdellodes ou Hirudinees 
et les Tr6matodes marins," 1868, page 107. 
This worm I found three times on the gills of the Ling ; one 
specimen on each. It is recorded from the Scottish coast by 
T. Scott* from the Lin". 
O 
The worm is 12-5 mm. long or longer, breadth about 2 mm, 
and expanding posteriorly into eight long fager-like processes, 
forming a sort of fan. Each process bears a cbitinous sucker, with 
which the worm is attached to the gills of its host. The head end 
is narrow and bluntly rounded; at the extreme anterior end there 
is a small circular oral sucker leading to a thin prepharynx and 
bulbous pharynx, and on each side of the prepharynx is a small 
sucker. A thin oesophagus leads to two sinuous intestinal lobes 
very much obscured by the vitellaria. The genital aperture is 
circular, placed just below the fork of the intestine, and bearing 
sixteen to seventeen cbitinous hooks, with their apices directed 
inwards. The ovary is situated at about the first third of the 
body, aud from it runs forward an oviduct leading to a winding 
uterus, expandirg greatly at the anterior end, and full of yellow 
eggs (0-20 mm. by 0-08 mm.) without filaments. Almost the 
whole body is taken up by the much developed vitellaria, which 
are united by two conspicuous longitudinal canals and a trans- 
verse one, each side uniting anterior to the ovary to open into the 
oviduct. 
• Scott, T, op. cit. Niueteeiitli Import, page 1 19, 
