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these continue to grow longer, they may be seen hanging into the 
concavity of the umbrella, where they then lie somewhat confusedly 
within the confined space there alloted to them. 
In the meantime, a velum has become developed from the margin 
of the umbrella, while the central portion of the gonophore containing 
the diverticulum from the coenosarc has become elongated between 
the four radiating canals, and may be seen projecting in the axis of 
the umbrella, as a wide coecal process, with distinct ectoderm and 
endoderm. It is easy to recognise in this process the manubrium of 
the medusa ; an oral aperture soon becomes formed at its extremity, 
and the little medusa, now expanding the margin of its umbrella, 
and everting its tentacula, escapes from the confinement of the eeto- 
theque, and enters upon the free phase of its existence. 
Laomedea dichotoma , Linn. 
Fine specimens of this zoophyte were obtained on the south-coast 
of Ireland, in the beginning of September, loaded with gonophores, 
containing medusae in various stages of maturity. The gonophores are 
compound, and consist of a blastostyle carrying numerous medusae, 
which increase in maturity as they approach the summit of the 
blastostyle, the whole being invested in an external capsule. 
The medusa, on its escape from the capsule, has a thin umbrella, 
which is capable of passing through almost every degree of con- 
vexity, from that of a nearly flat disc to that of a dome, embracing 
about ^d of a sphere, while it is often completely everted, so as to pre- 
sent the appearance of a wide hand-bell without the clapper, the ma- 
nubrium then representing the handle of the bell. This last condition 
is that which it always assumes when swimming, the manubrium 
being then invariably turned from the direction of motion. 
The base of the manubrium presents a hemispherical dilatation, 
and on its free extremity is borne a mouth with four well-developed 
lobes. Four radiating canals extend from the base of the manu- 
brium to the margin of the umbrella, where they enter a distinct 
circular canal. The margin of the umbrella carries sixteen filiform 
tentacula,* one of these tentacula being always situated at each 
junction of a radiating canal with the circular canal. The tentacles 
are thickly set with thread-cells, and their cavity presents the septate 
* Eighteen may frequently be counted, but this is probably abnormal. 
