HYDROIDS OF THE HAWAIIAN ISLANDS. 
955 
. Gonosome. — Gonangia borne on specialized hydrocladia with one or more hydrothecae at their 
bases, bean-shaped, arranged in 2 rows. The distal part of each of these specialized hydrocladia is 
curved and armed with strong nematophores, but without hydrothecae. They alternate irregularly 
with ordinary hydrocladia, the tendency being to an arrangement in which there are 2 ordinary 
hydrocladia; between adjacent phylactogonia. 
Locality. — Station 3852, off the south coast of Molokai, 47 to 115 fathoms. 
This is the smallest species of Lytocarpus found in the collection. It seems to be a very well- 
marked species, especially in its gonosome. 
Lytocarpus similis Nutting, new species. 
(PI. vi, fig 3; pi. xin, figs. 9, 10.) 
Trophosome. — Colony about 7 inches high, irregularly branched. Stem and branches fascicled. 
Hydrocladia alternate, often without distinct internodes, but with small internal thickenings just 
below the supracalycine nematophores and opposite the lower part of the hydrothecse. Hydrothecse 
deep, anterior outline concave, margin with 3 lateral teeth on each side and a rather longer anterior 
tooth. Supracalycine nematophore slender, terete, distinctly overtopping the hydrotheca; mesial 
nematophore short, not reaching the middle of the hydrotheca, regularly convex in outline. 
Gonosome. — Gonangia borne on modified hydrocladia which do not form pseudo-corbulse, but 
which are irregularly interspersed among normal hydrocladia. Each of these modified hydrocladia 
has a normal hydrotheca at its base, then one or more aborted hydrothecse, then globular gonangia 
arising regularly from aborted hydrothecse, each with a mesial and 2 supracalycine nematophores. 
Gonangia flattened, containing blastostyles supporting gonophores which are partly encircled by a 
sickle-shaped rim of ccenosarc. 
Locality . — Station 4000, southwest of the island of Molokai, 213 fathoms. 
This species is particularly interesting for two reasons. First, its gonosome furnishes a beautiful 
example of the homology between the gonophore and the hydranth, the former arising from aborted 
hydrothecse. Second, we have in this species a further proof, if any more is needed, of the fact that a 
classification of the genera of the Plumularidse can not be based on the trophosome alone, for the tro- 
phosome of this form is almost a typical Aglaophenia, while its gonosome is that of a true Cladocarpus. 
Genus HALICORNARIA. 
Trophosome. — Stem not fascicled. Hydrothecse with no posterior intrathecal ridge. Hydrocladia 
not branched and without septal ridges. 
Gonosome. — Gonangia borne on the stem or on the'bases of the hydrocladia, not taking the place 
of hydrothecse, and not protected by cotbulse or protective branches of any kind. 
Halicornaria flava Nutting, new species. 
(PI. vi, fig. 2; pi. xin, figs. 11, 12.) 
Trophosome. — Colony attaining a height of about 5 inches. Brownish yellow in color. Stem 
monosiphonic, not regularly branched, divided into regular internodes, each of which bears a hydro- 
cladium. Hydrocladia alternate; nodes not seen in profile, but marked by translucent lines when 
viewed by reflected light. Hydrothecse orbicular, large, margin with a single broad lateral lobe on 
each side, and one in front and another behind; a very strong anterior intrathecal ridge arising from 
above the middle of the hydrotheca and ending in a round knob at its center. Mesial nematophore 
attached throughout to the front of the hydrotheca and ending in a point projecting above the margin 
of the latter; the nematophore having a strong chitinous point at about its middle, projecting inward 
toward the hydrotheca, a unique feature in this genus so far as I know. Supracalycine nematophores 
short, triangular, not reaching nearly to the top of the hydrotheca. There are 2 strong, broad cauline 
nematophores at the front of the base of each hydrocladium. 
Gonosome. — Gonangia in the form of simple pyriform bodies arranged in a row along the front of 
the stem, one at the base of each hydrocladium. Their tops do not seem to have regular apertures of 
any kind, but simply to be ruptured by the escape of the sexual elements. There are no protective 
branchlets. 
Locality. — Station 3939, north of the island of Laysan, 163 fathoms. 
The bright brownish-yellow color of this species is quite conspicuous when the specimens are fresh. 
