112 Mr. D’Arcy W. Thompson on new Hydro-id 
I have little doubt that it coincides with the form noticed 
(and partly figured) by Dr. Coughtrey from Bluff Harbour, 
New Zealand, though the pinnje, according to his description, 
are jointed between each pair of hydrothecae. My specimens 
show the singular and conspicuous joint, to which he also re¬ 
fers, by which the pinnae arise from the main stem. 
Pericladium, Allman (modified). 
Trophosome. Hydrothecae more or less immersed, and closely 
set on all sides of stem and pinnae. 
Gonosome. Gouangia scattered, springing from between the 
hydrothecae. 
The above definition differs from that originally given by 
Prof. Allman in one point only, viz. in the omission of the 
clause relating to the general habit of the zoophyte. It stood 
as follows :— u Hydrothecae more or less immersed, and closely 
set round bifurcating ramuli , which spring from the sides of a 
common stem.” Although this was a marked and prominent 
feature of the species (a Japanese one) for which the genus 
was originally created, yet the arrangement of the hydrothecae 
is a still more important point, and the species about to be 
described agrees so closely in this respect with the type form 
that it is impossible to place the two in different genera. Prof. 
Allman, to whom I referred the point, agrees entirely with me 
on this matter, and says that u in young specimens and portions 
situated near the base of old ones, the ramification may be 
simple and pinnate, assuming only in adult specimens the 
normal character.” 
Pericladium novce-zelandice , sp. nov. (PI. XIX. figs. 3, 3 a.) 
Trophosome. Ilydrocaulus attaining a height of about 8 
inches. Main stem undivided, stout, cylindrical, and tapering 
from the base upwards. Pinnae for the most part alternate 
and subalternate, absent for about 2 inches at the base. Hy- 
drothecae very closely set, shortly tubular, adherent almost 
their whole length ; aperture wide, with about four small 
rounded teeth. 
Gonosome. Unknown. 
Locality. Pandora Bank, off Cape Maria Van Dieman, 
New Zealand, 15 fathoms (Dr. JoUiffe). 
I am much pleased to be able to make known this new and 
singular species. The two specimens I possess are, unfortu¬ 
nately, far from perfect: the hydrorhiza is wanting; they are 
destitute of gonangia; and the hydrothecse are a good deal 
shrivelled. They are covered in every part with diatoms, 
