30 
ment); but how, I am not able to decide. That they as true para- 
sites should feed directly on the tissues of the fish is possible, 
but seems less probable; neither in Hydrichthys nor in Nudi- 
clava åre the hydrorhizæ sunk into the skin, and the latter 
appears not to be affected by their presence (the same holds good 
for the Scopeli carrying Ichthyocodium); more likely they are mess- 
mates or commensals, feeding on leavings from the meals of the 
fish or perhaps on the excrement of the latter. I may add that 
I found no contents at all in the gastric cavity of the polypes of 
Ichthyocodium which I have cut in sections. 
Explanation of the plates. 
List of reference letters. 
ad = anus. 
da; == aåntennule. 
4g == antenna. 
f = furcal appendage. 
g —= genital segment. 
1 = chitinous thickening. 
m = manubrium of medusa-bud. 
md — mandibular palp. 
me = medusa-bud. 
mp; == maxilliped of first pair. 
mp, == maxilliped of second pair. 
— maxilla, 
0 — genital opening. 
P = polype. 
P1—P3 — first to third abdominal (thoracic) foot. 
pr —= lateral outgrowth from cephalothorax. 
v — marginal tentacle of medusa-bud. 
så = sipho. 
Plate I. 
Fig. 1: Scopelus glacialis Rhdt. with the combined parasite, co: of 
the Sarcotretes scopels (without egg-strings) and the Frk thyoondinmt | 
sarcotretis. X c. 2. 
: enltkged vi view of part of the same specimen of Sarcotretes (the 
stalk and proximal part of the swollen external portion) with part 
of the Hydroid-colony. me, = large medusa-bud having lost one 
of its marginal tentacles. 
| 
BO 
