378 . Prof. Allman on the Construction and 
minute polypoid trophosome, which he describes as bearing a close 
resemblance to the Campanularia raridentata, Alder. See Wright 
in Micr, Journ. n. s. vol. il. 
Thaumantias inconspicua, Forbes. 
Leptoscyphide. 
1. LeproscypuHus*, Allman, nov. gen. 
Trophosome.—Hydrocaulus simple or branching, attached by 
a creeping filiform hydrorhiza; hydrothece with an operculum 
composed of converging lanceolate segments. Polypites cylin- 
drical when extended; tentacula surrounding the base of a 
conical metastome. 
Gonosome.—Gonophores phanerocodonic. Umbrella, at the 
time of liberation, deep bell-shaped or conical ; manubrium 
pendent from a conical projection from the roof of the umbrella, 
of moderate size, with the mouth surrounded by four short capi- 
tate tentacula; radiating canals four, each terminating distally 
in a bulb, without evident ocellus, each bulb giving origin to a 
cluster of two or three tentacles; a single marginal tentacle 
with a bulbous base is also developed from the centre of each 
interradial space. 
I constitute the genus Leptoscyphus for a very minute Hydroid 
which I discovered some years ago in Orkney, where it occurs rather 
abundantly, creeping over the fronds of Laminaria digitata. I have 
already described it (Ann. Nat. Hist. Nov. 1859) under the name of 
Laomedea tenuis; but its remarkable Medusa, as well as the general 
characters of the trophosome, must certainly separate it from that 
genus. It will be noticed that the Medusa belongs to the type which 
is destitute of lithocysts, and has its generative elements developed in 
the walls of the manubrium, thus affording one of the two known 
exceptions to the rule that the Meduse of the Campanularian Hy- 
droids are of the type which carry lithocysts on the margin of the 
umbrella, and have their generative elements developed in special 
sexual buds which arise from the radiating canals,—the other excep- 
tion occurring in the Medusa which Agassiz has referred to Lafoéa 
cornuta, Lamx.t 
It will also be seen that the Medusa of Leptoscyphus resembles in 
all essential points the form for which Forbes has constructed his 
genus Lizzia; and I have little doubt that, when mature, its charac- 
ters would entirely correspond with this medusal type. I should 
accordingly have had no hesitation in assigning to the present Hy- 
droid the name of Lizzia, instead of constituting for it a new genus, 
were it not that Claparéde has found, in an undoubted Lizzia, that 
* From Aemrés, delicate, and oxvdos, a cup. 
_ t Thaumantias, though a Campanularian, is destitute of lithocysts, but 
its sexual buds are developed from the radiating canals. 
