1896.) BRITISH HYDROIDS AND MEDUSA. 489 
ment. Owing to the ripe state of the ova in some of the specimens, 
I was able to distinguish the species as Thaumantias buskiana, 
Gosse. It is quite distinct from Phialidium temporarium and 
Phialidium cymbaloideum, as the generative organs never extend 
along the outer half of the radial canals, and are always round 
or slightly oval in shape. 
It may be difficult to distinguish this species in its early stages 
from Phialidium temporarium. I have not yet met with the two 
species together; the latter appears in the spring and the early 
part of the summer, and the former in the autumn. 
Gosse named this species after Busk (1849), who described a 
similar medusa (without giving it a specific name) taken in the 
Solent during the autumn of 1848. 
Unfortunately Busk’s figures of the medusa are useless for 
identification. I believe that Busk took specimens of this species 
and also of other species which he has confused with it. 
Gosse was the first to give this species a description by which 
it may be readily identified. The following is an abstract of the 
description :—Umbrella when young globose, when older hemi- 
spherical or shallow campanulate, from 2 to 6 mm. in diameter, 
transparent and colourless. The margin of the umbrella fringed 
with 20-32 tentacles, very slender and extensile, with yellowish 
basal bulbs. A marginal vesicle between every two tentacles; some- 
times two vesicles present, and occasionally a vesicle has two 
otoliths. Ovaries small, oval, on the radial canals, containing 
globular ova in various degrees of development. Stomach small 
and quadrangular. Taken at Ilfracombe in the autumn. 
The Plymouth specimens agree with the description given by 
Gosse. 
The species closely resembles Phialidium variabile (Claus), from 
the Mediterranean. I prefer to keep them separate for the 
present until the hydroid forms have been identified. 
Italso closely resembles the figure given by Forbes of Thawmantias 
thompsoni, which was taken by Forbes on the coast of Cornwall 
and in Roundstone Bay on the west coast of Ireland. 
Bohm (1878) has described the medusa under the name of Clytia 
johnstont from Heligoland. 
Hartlaub (1894) has recorded Phialidium variabile (Claus) (not 
Haeckel) from Heligoland. 
PHIALIDIUM TEMPORARIUM, Browne. (Plate XVII. figs. 4, 5, 6.) 
I find it is necessary to give a specific name to one of the 
commonest medusz on our coasts. It is probable that Forbes 
described this species under the name of Thaumantias hemispheerica, 
but as Haeckel has taken Thaumantias hemispherica as the type of 
the genus Thaumantias, and many other naturalists have placed 
the species upon their lists, it is necessary to retain it. I have 
already described some specimens of this species under the name 
of Phialidium variabile, Haeckel, in the ‘ Report on the Isle of 
Man Meduse’; but I have since discovered that Phialidiwm 
