EEPOET OX THE HYDEOIDA. 
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Thuiaria pectinata, n. sp. (PL XXXIII. figs. 1, la). 
Trophosome . — Stem unbranched, monosiplionic, set with equidistant, opposite pinnae, 
pinnae usually with a joint occurring at no definite distance from the base. Hydrothecse 
borne both by stem and pinnae, opposite on stem, subopposite on pinnae, conical, 
deep, adnate to the hydrocaulus for their entire height, and thence prolonged for a short 
distance by a free, thin, membranous extension of their walls. 
Gonosome not present. 
Locality. — Simon’s Bay, Cape of Good Hope. 
Thuiciria pectinata is a very elegant little species, attaining a height of between 
two and three inches. It is of a rather rigid habit, and in its exactly opposite pinnae it 
presents a feature which is as unusual as it is striking. 
The pairs of pinnae are situated at equal distances, being separated from one another 
by three pairs of opposite hydrothecse. 
The hydrothecae proper are entirely adnate to the hydrocaulus, but their walls are 
continued for a short distance in the form of a free, very thin, membranous tube, which, 
however, is not always preserved in the specimen. 
The hydrothecae are exactly distichous, and follow one another at very short 
intervals. 
TKuiaria hyalina, n. sp. (PI. XXXIII. figs. 2, 2a). 
Trophosome . — Stem fascicled, sending off pinnately disposed, alternate ramuli, 
whose perisarc is colourless and transparent. Hydro thecae borne both by stem and 
pinnae, cylindrical, slightly tumid below, adnate to the hydrocaulus for their entire 
height, and gently curving away from the axis ; orifice with four indistinct cusps. 
Gonosome not present. 
Locality . — Station 126, south of Pernambuco; lat. 10° 46' S., long. 36° 2' W.; 
depth, 770 fathoms. 
The specimen of Thuiaria hyalina contained in the collection is but fragmentary, 
and has a height of upwards of three inches. The stem is strongly fascicled below, but 
becomes monosiphonic towards its distal end. It carries along its length short, simple 
ramuli, with a regularly pinnate disposition. 
The ramuli and the monosiphonic portions of the stem are perfectly transparent and 
colourless, and allow a good view to be obtained of their contents. These, in some parts 
of the specimen, have been well preserved, and afford evidence of the remarkable fact that 
in this species the hydranths are but imperfectly retractile. The greater part of the body 
