OF THE ‘PORCUPINE’ EXPEDITIONS. AT7 
it better to employ the existing name of Halicornaria (though in a sense somewhat 
different from that assigned to it by Busk) for such Plumularide as possess the tropho- 
some of Aglaophenia but have their gonangia destitute of corbule or other protection. 
Among British species the genus would include the Plumularia pennatula of Lamarck. 
HALICcORNARIA RAMULIFERA. Plate LXVII. figs. 3, 3°, 3’, 3°, 3% 
Trophosome.—Stem attaining a height of about an inch and a half, slightly recurved, 
simple, fascicled below, but becoming single towards the summit; pinne alternate, borne 
each upon a short process of the stem and extending along the stem for about three 
quarters of its entire height, longest towards the centre of the series, where they have 
a length of about two lines, and thence decreasing in length upwards and downwards, 
jointed, with each joint supporting a hydrotheca, and with its cavity constricted from 
distance to distance by imperfect septa. Hydrotheca adnate to the pinna for a little 
more than half its height, free for the remainder, adnate portion tumid, free portion 
funnel-shaped, abruptly bent forwards, with its anterior wall forming nearly a right 
angle with the adnate portion and having the margin deeply serrated ; no intrathecal 
ridge; mesial nematophore detached from the hydrotheca, and forming a stout free 
tubular spine opening by a slit along that side which faces the hydrotheca; lateral 
nematophores forming a pair of short tubular diverging spines; a long jointed usually 
simple ramulus, destitute of hydrothece, given off from every joint of the pinne 
between the fundus of the hydrotheca and the mesial nematophore, emitting nemato- 
phores from distance to distance and curving over the hydrotheca towards the distal 
extremity of the pinna; main stem carrying a pair of nematophores at the base of 
every pinna. 
Gonosome.—Gonangia (female ?) ovate, with truncate summit, each springing from the 
front ci1one of the processes which are emitted by the main stem for the support of the 
pinne. 
This is a very distinct and well-marked form. It will be easily recognized by the 
funnel-shaped and abruptly divergent distal portion of the hydrothece, and by the long 
ramuli, which do not develop hydranths and which are emitted by the pinne at the base 
of each hydrotheca. It is also rendered very remarkable by the way in which the 
accessory ramulus interposes itself between the hydrotheca and its mesial nematophore. 
It plainly constitutes a connecting link by which 4glaophenia passes into Plumularia. 
Halicornaria ramulifera was obtained in the deep cold area along with Thuiaria laxa, 
Thuiaria hippuris, and Lafoéa halecioides, from a depth of 640 fathoms, where the 
thermometer registered 30° Fahr., thus living in a temperature which was 2° Fahr. 
below the freezing-point of fresh water. 
Ciabocarpus, Allman. 
Trophosome.—Hydrocaulus with pinnate ramification. Hydrothece with an intra- 
VOL. ViI.—PaRT vil. April, 1874. 3x 
