44 
THE VOYAGE OF H.M.S. CHALLENGER. 
magnifying power they give a hirsute appearance to the surface of the colony. They are 
in the form of very slender cylindrical tubes, open at the summit, and contain a granular 
matter which is directly continuous with the contents of the peripheral tube from which 
they spring. In Perisiphonia Jilicula similar receptacles occur in connection with the 
axial system, one being here fixed on the peduncle of every hydrotheca, while the lateral 
offsets of the axial tube in this species carry each a pair of such bodies near their origin. 
These little receptacles must certainly be regarded in the same light as the sarco- 
thecse or nematophores so characteristic of the Plumularinse, which in some rare cases are 
also present in a modified form among other groups of the Hydroida. 
That their contents, like those of the nematophores of the Plumularinse, consist 
essentially of sarcode — whether in connection with a true cell-tissue or not — there can be 
very little doubt, and, judging from the analogy of the Plumularinse, it is also nearly 
certain that, like the sarcothecse of these, their contents have the power of emitting 
pseudopodial extensions of the enclosed sarcode. 
A living specimen of a Perisiphonia must thus when seen under the microscope present 
an appearance as singular as it must be beautiful ; for besides the flower-like hydranths 
which expand over the surface of the colony, countless fine contractile filaments of sarcode 
will be seen like the pseudopodia of the Foraminifera extending in all directions into the 
surrounding water. 
Perisiphonia Jilicula, n. sp. (PI. XXII. figs. 1-4). 
Trophosome. — Colony attaining a height of between two and three inches, stem 
simple or sparingly branched, and very regularly set with pinnately disposed opposite 
or subopposite ramuli. Hydrothecse flask-shaped, curving away from the axial tube, 
and with the neck short and stout. 
Gonosome not known. 
Locality. — Station 75, near the Azores; lat. 38° 38' 0" N., long. 28° 28' 30" W.; 
depth, 450 fathoms. 
Station 163a, off Twofold Bay, Australia; depth, 150 fathoms. 
Perisiphonia Jilicula is a rather strong, rigid species, and in common with Peri- 
siphonia pectinata, presents in its nearly opposite ramuli a distinct and easily recognised 
physiognomy. The somewhat robust stem springs from a complex plexus of tubular 
filaments, and soon begins to send off from each side its pinnately disposed ramuli. 
These are considerably more slender than the stem, and are either opposite or so nearly 
opposite that close inspection is necessary in order to discover any deviation from an 
exactly opposite arrangement. This deviation, however, becomes sufficiently obvious 
when the pinnae are traced to their origin from the axial tube of the stem. It is only 
