13 
adaptation. With regard to the supposed resemblance between the 
medusa of the latter and the Sarsia medusæ, I am unable to see 
any likeness at all. On the other hånd, the medusa of Hydrichthys 
mirus , as figured by Fewkes (PI. V), is a typical Tiarid medusa: 
the manubrium which is cross-shaped in transverse section; the 
compressed, triangular tentacular bulbs; the characteristic basal 
bending of the tentacles; and the development of two opposite 
tentacles before the two next ones; everything points towards the 
Tiaridæ and is in absolute contradiction to the Codonidæ. The 
same holds good for Hydrichthys boycei Warren. Warren (1916) 
rightly remarks (p. 180): “The medusa ... recalls the medusa of 
Perigonimus", and (p. 183): “. . . Hydrichthys shows marked simil- 
arities to Perigonimus, and very possibly the differences which 
occur have arisen through adaptation to the parasitic habit”. Warren, 
like Fewkes, indicates, though with duly reservation, the possi- 
bility of a connection between Hydrichthys and Siphonophores. 
Another peculiar hydroid, Ichthyocodium sarcotretis, was described 
by Jungersen (1911). It is epizoic on a copepod, Sarcotretis 
scopeli, parasitic on the fish Scopelus glacialis of the northern At¬ 
lantic area. The polyps are devoid of tentacles, and some of them 
bear clusters of medusoid gonophores with two large opposite tent¬ 
acular bulbs. Jungersen points out (pp. 25 and 27) the close 
resemblance between this interesting hydroid and Hydrichthys mirus 
Fewkes. With regard to the systematical position, Jungersen 
quotes the assertion of Stechow, mentioned above, and says: 
“Also Hydrichthys is referred by Stechow to the Corynidce; in 
so far as this will prove to be well founded, our Ichthyocodium 
has to be included in the same family” (p. 27). — As in Hydrich¬ 
thys , the gonophores of Ichthyocodium with the two large, triang¬ 
ular tentacular bulbs opposite each other, point distinctly towards 
the Tiarid medusæ. I am not convinced, however, that the gono¬ 
phores of this species develop into free medusæ. In spite of a 
single remark (“In transverse sections the cavity of the manu¬ 
brium is quadrangular”, p. 23), I do not think that Jungersen 
has cut microtome sections of this species; in any case, I have 
found no preparates among the effects left by his death. This is 
deplorable, because [some sections, made by me for comparison 
with Kinetocodium, seems to show that to a certain degree J u n- 
