132 
The manubrium is of moderate size. It is a sub-cylindrical body, 
somewhat dilated at its base, and having its oral extremity sur- 
rounded by four short tentacles. These manubrial tentacles have 
the cells of their endoderm so disposed as to give rise to the appear- 
ance of a transverse segmentation of their cavity, and the extre- 
mity of each is surrounded by a little capitate group of thread-cells. 
The cavity of the manubrium is lined with cells containing red 
granules. 
From the base of the manubrium four gastrovascular canals ra- 
diate towards the margin of the umbrella, to open there into a distinct 
circular canal. 
At each of the four points where the radiating canals open into 
the circular canal, is a large bulbous dilatation of the gastrovascular 
system. Its cavity contains red pigment granules, and while at its 
proximal side it is in communication with the radiating and circular 
canals, it sends off from its distal side two filiform contractile ten- 
tacula ; the margin of the umbrella being thus furnished with eight 
tentacles, arranged in four equidistant groups of two each. At the 
root of every tentacle is a black <e eye-speck.” The velum is mode- 
rately developed. 
From an ordinary-sized specimen of this eudendrium, kept alive in 
an 8 oz. phial of sea-water, the medusae were thrown off in such 
multitudes as to give a milky cloudiness to the water. They con- 
tinued active with me for more than a week ; but during that time 
no further change of form occurred, and no generative elements were 
developed in them.* 
If we endeavour to trace the development of the gonophore from 
its earliest appearance to the complete formation of the medusa, 
we shall find that it originates as a minute solid bud from the side 
of the branch. In this bud a cavity may be seen communicating 
* Gegenbaur has already referred the medusal genus, Bougainvillea, to euden- 
drium as its u nurse” form, and it is evident that the little medusa here de- 
scribed needs only that the number of tentacles and ocelli composing each 
marginal group shall become multiplied, and the oral tentacles become bifur- 
cated, in order that it may be converted into a true Bougainvillea. This 
change I have not witnessed, for my continued observation of the medusas was 
here interrupted ; but Dr Strethill Wright, who obtained the same species of 
eudendrium in the Firth of Forth, informs me that he has traced its medusae 
into the adult Bougainvillea, with the generative elements developed in the 
base of the manubrium, as is well known to be their situation in this genus. 
