25 
they, too, are devoid of tentacles and (probably) possess a 
mouth-opening, the terminal end sometimes appearing trumpet- 
shaped. 3) The medusæ. The largest buds are elongated, cylin- 
drical; in the fixed state they do not develop more than two, 
clumsy tentacles; their surface is speckled with nematocysts (most 
distinctly seen in the younger stages, still before the medusoid 
shape is recognizable). When liberated — the fish was kept in an 
aquarium, and great numbers of medusæ were set free — they at 
first resemble a young Stomatoca (the medusa of Perigonimus), 
having an ovoid, upwards rounded beil, four simple radial canals 
and ring-vessel, and a proboscis with entire mouth. Later the 
medusa acquired four tentacles, two new growing out in the inter- 
space of the two first formed. When all four are fully developed 
it resembles a Sarsia. In this stage, possessed of four long and 
siender tentacles, the medusæ sank to the bottom and died. 
If we suppose that the medusæ of Ichthyocodium , when set 
free, also acquire four tentacles — which seems to me at least 
probable — they would agree with those of Hydrichthys ; in the 
attached state, as buds, the likeness is practically complete. The 
differences of some amount between Hydrichthys and Ichthyocodium 
are the following: 1) the basal membrane in the first is firm, leathery; 
2) the polypes are of two kinds, sterile and fertile ones; 3) the 
medusæ-buds are clustered on the ends of branches or stalks from 
the fertile polypes. According to the figures given by Fewkes 
* 
(the author does not give any measurements of the polvpes, buds or 
medusæ), the size of the colonv in Hydrichthys surpasses that of 
the largest Ichthyocodium found; but it is by no means impossible 
that the latter may acquire a larger size and fuller development 
than the specimen figured PI. I, lig. 1. 
In 1907 K. E. LI oyd described a Nudiclava monocanthi 
growing on the fish Monocanthus tomentosus from the Andamana- 
Sea (13). Like the preceding this Hydroid is attached by means 
of a naked basal membrane, containing tubes from which naked, 
claviform hydranths without tentacles grow (0,75 mm. in length); 
