1896.] BRITISH HYDROIDS AND: MEDUS £. 479 
taken, and found a few specimens agreeing with Agassiz’s 
description of Margellium gratum, both in the number of marginal 
tentacles, and in the number of clusters of nematocysts on the 
oral tentacles. I think this removes all doubt concerning the 
identity of the two species. 
In the Valencia specimens the clusters of nematocysts develop 
in the following order :—The earliest stage has each oral tentacle 
terminating in a single cluster of nematocysts. A second cluster 
appears near the first cluster upon a short stalk; the tentacle then 
appears bifurcated, each branch terminating in a round cluster of 
nematocysts. Two more clusters, each on a short stalk, make 
their appearance, one on each side of the tentacle, about the middle 
of itslength. This was usually the appearance of the oral tentacles 
in all the large specimens taken at Port Erin and at Plymouth. 
At Valencia, in a few of the largest specimens, with four or five 
tentacles in each perradial group, I observed on each oral tentacle 
a second pair of lateral clusters of nematocysts, below the first 
pair. One specimen had a fifth cluster on a short stalk situated 
midway between the two terminal clusters. This agrees with the 
development of the clusters described by Agassiz in Margellium 
gratum. Another specimen, however, showed a variation in 
development, by possessing three terminal clusters and only a 
single pair of lateral clusters. 
Allman (1859) has described and figured a Calyptoblastic hydroid, 
Laomedea tenuis [= Leptoscyphus tenuis, Hincks (1868)], which he 
found at Stromness. The hydroid has gonothece each containing 
a medusa. Allman has not given any description of the medusa 
inside the gonotheca, and from the figure it is impossible to 
identify it, chiefly on account of its being at a very early stage in 
development. Allman found inside the jar containing this hydroid 
a number of young medusz which he believed to be closely related . 
to the genus Jzzzia. From the description given of these meduse I 
believe they are probably an early stage of Margellium octopunctatum. 
Allman regards these free-swimming medusz as the medusa of the 
hydroid in the jar. This observation has never been confirmed, 
and if it be true, then a case is established in which a Calypto- 
blastic hydroid produces Anthomedus=. 
Allman does not state that he has seen a single medusa leave the 
hydroid nor show in any way that the medusa inside the gonotheca 
resembles the free-swimming Lizzia. I do not think that there is 
sufficient evidence to prove that the meduse came from the hydroid, 
and I hesitate to accept the statement until the observations have 
been confirmed. It is quite possible that the young Lizzia 
entered the jar along with the sea-water. 
Distrisution. America—Massachusetts Bay, Agassiz. Norway, 
Sars. France—Wimereux, Giard. 
Scotland—Shetland Islands, Forbes. St. Andrews, M‘Intosh. 
England—Plymouth, Garstang; Allen. Fowey, Peach. 
Falmouth, Vallentin. Isle of Man, Browne. | 
Ireland—Valencia Island, Z. 7. B. 
