58 Prof. Allman on the Hydroida. 
almost exclusively on the hydrocaulus, only an occasional one 
being here and there developed from the hydrorhiza, while in 
P. palliatus they are confined to the hydrorhiza,—and in the form 
of the medusa, whose contracted codonostome gives to the um- 
brella, at the time of liberation, an oviform shape which is very 
striking and peculiar, while in P. palliatus the umbrella does not 
become contracted towards the codonostome, and is accordingly 
nearly cylindrical in form *. 
In meduse now about the tenth day since their liberation, 
and still alive in my tanks, the form has undergone considerable 
change, the umbrella having become nearly spherical, thus pre- 
senting a further departure from the medusa described by Dr. 
Wright as proceeding from P. palliatus. No increase, however, 
has taken place in the number of marginal tentacles. 
Bougainvillia fruticosa, Allman, n. s. 
Trophosome.—Hydrocaulus rising to the height of about two 
inches, much branched, with the main stems composed of aggre- 
gated tubes, branches subalternate, periderm of the smaller 
branches marked by shallow transverse corrugations, which 
become obsolete on the larger branches and main stems: poly- 
pites im extreme extension nearly cylindrical, with the periderm 
continued for a short distance over the posterior part of their 
body as a thin pellicle, which in extreme contraction appears as 
a membranous corrugated cup, into which the polypite has 
become withdrawn for about its posterior third. 
Gonosome.—Gonophores pyriform on distinct peduncles spring- 
ing from the upper side of the ultimate ramuli, along which they 
extend nearly from the origin to the termination of the ramulus. 
I met with B. fruticosa in September, growing in abundance 
on a large piece of floating timber in the mouth of the Kenmare 
River, coast of Kerry. 
Bougainvillia fruticosa, though closely allied to B. ramosa, Van 
Ben., differs from it in the more cylindrical and slender form of 
the extended polypite, in the less extent to which the polypite is 
invested by the membranous dilatation of the chitinous periderm, 
and in the disposition of the gonophores. While in B. fruticosa 
the polypites in extreme retraction have the tentacles and nearly 
two-thirds of the body exposed, the contracted polypites of B. 
ramosa are almost entirely concealed within the dilated periderm. 
In B. ramosa, moreover, the gonophores, instead of being borne 
along the whole of the upper surface of the ultimate ramuli, are 
confined to their distal extremity, where they occur singly or 
in a pair consisting of two opposite gonophores, or else in an 
* See Dr. Wright’s description of Atractylis pallida, in Ann, Nat, Hist. 
for Aug. 1861, p. 129, pl. 4. figs. 6 & 7. 
