1896.] BRITISH HYDROIDS AND MEDUSA. 467 
Amphicodon globosus, Haeckel (1879). 
Amphicodon amphipleurus, Haeckel (1879) ; Garstang (1894) ; 
Allen (1895). 
The different stages in development of this medusa having been 
taken in localities far apart, and the wrong hydroid form assigned 
to one of them, has led to six distinct species being recorded. 
Haeckel retains four of these and places two amongst the synonyms. 
I have recently given an account of this interesting medusa in 
the Report on the Medusz of the Isle of Man, and here only givea 
summary with some additional notes on the occurrence of the 
medusa at Plymouth and Valencia Island. 
The great abundance of this medusa at Port Erin during 1893 
and 1894 enabled me to identify the early stages as species already 
described. 
The first stage has only one tentacle, to which belongs Steen- 
strupia (Amphicodon) globosa, Sars, but only those specimens 
described with one tentacle. 
The second stage has a single group of two tentacles, to which 
belongs Coryne (Amphicodon) fritillaria, Steenstrup. 
The third stage (adult) has a single group of three tentacles, to 
which belong certain specimens of Steenstrupia (Amphicodon) 
globosa with three tentacles and Amphicodon amphipleurus, Haeckel. 
The medusa first reproduces by means of numerous buds at the 
base of the tentacles, and when gemmation is about fo cease ova 
or spermatozoa appear upon the walls of the stomach. The sexes 
are separate, and the ovum finally develops into a Corymorpha-like 
hydroid. The development takes place inside the umbrella-cavity, 
and the hydra remains attached to the wall of the stomach until 
two verticils of tentacles are formed. Steenstrup described the 
medusoid Coryne fritillaria from free-swimming specimens, and 
also dredged a hydroid having a single verticil of tentacles, and 
meduse attached to it, without tentacles, but with an oblique 
margin to the umbrella—one of the characteristic features of the 
free-swimming meduse. He naturally considered this hydroid to 
belong to the medusoid Coryne fritillaria. It is clear, however, 
from the development of the hydroid within the umbrella-cavity, 
that the hydroid must have two verticils of tentacles. 
The hydroid has not yet been taken in the British area, but it is 
evident from the distribution of the medusoid form that it must 
exist in more than one locality. It may be difficult to recognize 
the hydroid form without its medusa-buds ; but with medusez, the 
presence of the five longitudinal bands of nematocysts upon the 
ex-umbrella of the medusa ought at once to establish its identity 
and to distinguish it from Corymorpha nutans. 
Valencia.—On the first day of tow-netting, April 5th, a single 
specimen was taken, and about two dozen more during the next few 
days, but not one was seen after April 16th. The specimens were 
similar to those taken at Port Erin. Some had ova upon the wall 
of the stomach; others had young hydre either attached to the 
stomach or free within the umbrella-cavity. e 
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