104 
Mv. D’Arcy W. Thompson on new Hydroid 
part, globular, smooth ; margin slightly everted ; orifice with 
a round operculum. 
Locality. Sealer’s Cove {Dr. Ferd. Muller). 
In the wide space which separates the pairs of hydrothecse 
this species approaches Dynamena distans of Lamouroux. The 
two forms, however, have no other character in common. 
A little cluster of specimens without gonangia, and from 1 
to 3 inches high, which I have no doubt represent a young 
form of this species, are contained in Dr. Harvey’s collection 
from Circular Head, Tasmania. They show the hydrorhiza 
to be fibrous, creeping, and inconspicuous. They have the 
stem rather stronger and the hydrotheca a little larger than is 
the case in the type specimens. 
Sertularia jlosculus, sp. nov. (Pi. XVII. figs. 2, 2 a.) 
TropJwsome. Hydrorhiza consisting of a slender creeping 
filament. Ilydrocaulus attaining a height of about § of an 
inch, very delicate. Pinnae alternate, nearly perpendicular 
to the main stem. Hydrothecse, on the pinnae, opposite, in 
pairs, closely adnate, one pair to each internode ; on the stem 
subalternate, one in the axil of each pinna. Hydrothecae shortly 
tubular, divergent for about half their length; orifice small, 
looking upwards, with two short teeth. Colour yellowish 
white. 
Gonosome. Unknown. 
Locality. Profusely clothing a Fucus from Australia (Ade¬ 
laide?) {Dr. Ferd. Muller). 
This is a singularly delicate and beautiful species, which, 
however, becomes greatly shrivelled in the process of drying. 
It has some affinities, and may possibly prove identical, with 
Dynamena divergens of Lamouroux. 
Sertularia minima. (PI. XVII. figs. 3, 3 a, 3 b.) 
Synthecium gradle, C ought re j, Trans. N.Z. Inst. vol. vii. p. 286. 
Sertularia pumila, Coughtrey, Ann. & Mag. Nat. Hist., Jan. 1876. 
Trophosome. Hydrocaulus simple, attaining a height of T 
to ’25 inch, springing from a delicate creeping hydrorhiza 
which forms a filamentous network overrunning seaweeds; 
branches erect; internodes marked off by a deep constriction. 
Hydrothecse small, tubiform, adnate nearly their whole length, 
closely approximated; orifice cleft, forming two teeth. 
Gonosome. Gonangia, one to each hydrocaulus, arising from 
a point just below the lowest pair of hydrothecse ; globular or 
somewhat pear-shaped ; margin slightly everted, entire. 
