388 
KATHLEEN HADDON. 
I should also like to thank the trustees of the Bathurst 
Fund, Newnham College, for a grant awarded to me in the 
summer of 1911. 
II. Material. 
The copepods were found attached to specimens of the 
polycluete worm Harmothoe, and all were fixed incorrosis'e 
and acetic and preserved in 70 per cent, alcohol. 
There were seven worms and ten parasites, distributed as 
follows : three worms had one parasite each on the head, two 
worms had one parasite each on a parapodium, one worm had 
a parasite on tlie head and another on a parapodium, and one 
worm had three parasites on tlie head. 'I'he parasites were 
always attached to the dorsal surface of the host. 
III. Anatomy. 
A. Tlie Female. 
1. External Appearance. — The female is entirely 
devoid of appendages, and the portion outside the host is 
globular in shape, except for swellings at the bases of the 
egg-sacs ; in some of the smaller forms, which are probably 
young as their egg-sacs are not developed, there is a tendency 
for the body to be flattened ventrally. Levinsen (9) des- 
cribes Herpyllobins arcticus as being triangular in 
outline and laterally compressed, but Kroyer’s description (7) 
of a sac-like body seems to tally better with this form. The 
body is smooth and of a white or yellowish colour, and some 
specimens show the slight longitudinal grooves, mentioned 
by Steenstrup and Liitken (12), which, as they were observed 
in fresh specimens by Mr. Potts, cannot be due to shrinkage 
in spirit, as was suggested by these observers. 
'I'he length of this part of the parasite is from 1 to P3 mm. ; 
Levinsen (9), in his summary of the specific characters of 
H. arcticus, gives the length as P5 to 2 min., but on p. 367 
he gives lengths varying from 0'6 to 2 mm., so that there is 
