1896.) ° BRITISH HYDROIDS AND MEDUS. 465 
elongate and are soon seen to be dilated into bulb-like expansions at 
their extremities. The bulbs increase in size and come in contact 
by their sides; while one of them, enlarging much more rapidly 
than the other three, gives a marked preponderance to its side 
of the bud and makes the distal end of the bud appear obliquely 
truncated. It then begins to extend itself beyond this distal end 
into a thick hollow tentacle.” 
Allman also obtained free-swimming medusz from his hydroids, 
which he has described and figured in his monograph. These are 
similar to the figures given by Hodge, and have a margin at right 
angles to the longitudinal axis of the umbrella. 
From the description given by Allman of the development of the 
medusa, it appears that the rapid growth of the large tentacle-bulb 
extends the length of the umbrella more on that side than on the 
other, and in this way the margin becomes oblique, as one side of 
the umbrella is longer than the other. It is clear from the de- 
scriptions given by Hodge and Allman, that the obliqueness must 
disappear before the medusa is liberated, as they figure the free- 
swimming form with the margin in the normal position. I think 
that these observations on the obliqueness of the margin of the 
umbrella strengthen the view that the British and Norwegian 
specimens belong to the same species, and I have again united 
them under the old name of Corymorpha nutans. 
Forbes has given only two species in his medusoid genus Steen- 
strupia, namely S. rubra and S. flaveola, I agree with Haeckel 
in considering that these are not distinct species. The character- 
istic features of these meduse are similar to those of the medusz of 
Corymorpha nutans. 'The figures given by Forbes of Steenstrupia 
show the characteristic points of the species, but they are not 
good figures of a healthy specimen of the medusa of Corymorpha. 
Hodge recognized the similarity between Steenstrupia and the 
medusa of Corymorpha, but was led by Forbes’s figures to consider 
the latter as another species. 
Allman states the medusa of Corymorpha “belongs to a form to 
which Forbes has given the generic name of Steenstrujia.” Sars 
(1877) writes, “It is even not improbable that when disconnected 
from the parent animal, they (the medusz) may develop themselves 
into the species described by Forbes under the name of Steenstrupra 
rubra.” 
During my visit to Valencia Island in 1895, 1 found meduse 
corresponding to the descriptions and figures given by Hodge and 
Allman of the medusa of Corymorpha nutans (P). XVI. fig. 1). They 
were often exceedingly abundant during April and May, and some 
occasions many hundreds could have been quickly collected. One 
day I thought that a lovely Siphonophore had entered the net, but 
closer examination showed some dozens of these medusz, caught 
by the tentacle, on a piece of cotton about an inch and a half long. 
The umbrella is bell-shaped, nearly twice as long as wide; the 
aboral end of the umbrella is extended into a spine-like process, 
which is always present, and is a characteristic feature of the 
Proo. Zoon. Soc.—1896, No. XXX. 30 
