REPOET ON THE HYDROIDA. 
73 
Gonosome not present. 
Localities . — Off Somerset, Cape York, Torres Strait; depth, 8 to 12 fathoms. 
Bahia ; depth, 10 to 20 fathoms. 
This is a graceful plumose form, attaining a height of about three inches, and 
exceptional among the species of Desmoscyphus in having the hydrothecse which 
compose each pair in the pinnae not strictly opposite, but so disposed that a line joining 
the centres of both will be oblique to the axis of the pinna. 
"While the hydrothecse of the pinnae, notwithstanding this obliquity, are adnate to 
one another by their opposed sides, those of the stem are widely separate. Here they 
are alternate and smaller than those of the pinnae, while every internode carries two on 
one side and one on the other; one which is somewhat smaller than the others being 
always borne in the axil of a pinna. 
Desmoscyphus obliqua was dredged from widely separated localities — Torres Strait, 
where it occurred at a depth of from 8 to 12 fathoms, and off Bahia, where specimens 
were brought up from depths of 10 to 20 fathoms. 
Desmoscyphus acanthocarpus, n. sp. (PI. XXXV. figs. 2, 2a, 2b, 2c). 
Trophosome . — Stem monosiphonic, unbranched, carrying alternate pinnse ; stem and 
pinnse composed of well-defined internodes, every internode carrying a pair of opposite 
hydrothecse which are connate in the pinnse but disjunct towards the proximal end of the 
stem. Hydrothecse deep, tubular, adnate to the front of the internode for nearly their 
entire height ; margin of orifice having at its epicauline side a wide sinus, the edge 
of which supports a thin, membranous, hood-shaped operculum which arches over the 
orifice. 
Gonosome . — Gonangia elongated pyriform, with the axis slightly curved, springing 
with an alternate disposition each by a very short peduncle from an internode of the 
main stem just below the base of a hydro theca, terminating distally in an even circular 
orifice, and thickly set with minute spines. 
Locality. — Off Bahia ; depth, 10 to 20 fathoms. 
Desmoscyphus acanthocarpus is a curious and interesting species. The hydrothecse 
along the entire length of the pinnately disposed ramuli are all brought to one side of 
the ramulus, and are here connate to one another for nearly their entire height. Those 
which are borne by the stem are similarly connate towards the distal end of the stem, but 
towards the proximal end they become disjunct and more and more widely separated from 
one another, until ultimately they lie in two exactly opposite marginal series. The stem 
for some distance from its hydrorhizal end is destitute of hydrothecse, and here forms a 
(zool. chall. exp. — part lxx. — 1888.) Aaaa 10 
