936 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
remember that there are 32 species of that genus in Australian waters, as shown by “< 
Bale in his Catalogue of Australian Hydroids. 
Hydroids were secured at 37 stations during the Hawaiian cruise, and at depths 
ranging from 10' to 500 fathoms. At 20 of these stations the depth was over 100 
fathoms. The bottom was exceedingly rough almost everywhere, making successful 
dredging unusually difficult. The region is undoubtedly one favorable to hydroid 
life, and the depth at which the dredging was done was within a range which 
furnishes suitable conditions for both shallow and deep water forms. Notable hauls 
were made at the following stations: 
Station 3851, off south coast of Molokai Island, 134 fathoms; 8 species. 
Station 3859, between Molokai and Maui islands, 138 fathoms; 9 species. 
Station 3939, off Laysan Island, 163 fathoms; 6 species. 
Station 4098, off north coast of Maui Island, 95 fathoms; 6 species. 
Station 4802, between Maui and Molokai islands, 122 fathoms; 6 species. 
It is worthy of note that all of these hauls are in depths of from 95 to 163 
fathoms. 
SYSTEMATIC DISCUSSION. 
HYDRODENDRIDA, new family. 
Trophosome . — Colony branching, the hydrocaulus being composed of a spongy mass of chitinous | 
tissue, which is covered with an external coating of naked coenosarc. Hydranths with a single 
whorl of filiform tentacles and a flat hypostome, resembling the oral disc of an actinarian. 
Gonosome . — Sexual products borne in large hernia-like protuberances from the hydranth bodies. 
No sign of medusoid structure or of a blastostyle. Colonies bisexual. 
HYDRODENDRITJM Nutting, new genus. 
There being but a single known representative of the family, the generic definition can not 
at present be constructed, but will have to be essentially that of the family. 
Hydrodendrium gorgonoides Nutting, new species. 
(PI. i, figs. 1-6; pi. vu, figs. 1, 2.) 
Trophosome . — Colony flabellate in form and attaining a height of a foot or more, judging from 
the much-broken pieces secured. Hydrocaulus very woody and thick, the main stem in some 
places being as much as | of an inch in thickness. The superficial fibers of which the hydrocaulus 
is composed are in general parallel, and ascend in a twisted or spiral manner. Branches very <y . 
irregular and dendritic, the ultimate branchlets sometimes anastomosing to a limited extent. 
Hydranths irregularly scattered over the stem and branches, but showing a tendency to aggregate 
in the angles between adjacent branches and in the protected portions of the meshwork formed 
by the anastomoses of the terminal branchlets. Hydranths with a cylindrical body, which is } 
rather short and stout in preserved specimens, an oral surface resembling the oral disc of simple 
actinians, and a single whorl of filiform tentacles around the margin of the disc, the tentacles 
having a somewhat nodulated appearance, owing to the presence of nematocyst batteries. The 
individual hydranths arise, not from a single coenosarcal tube, but from several distinct filaments 
from the free ceenosarc with which the hydrocaulus is covered. (See figure 1.) 
Gonosome . — The gonophores, if it is proper to call them such, are in the form of immense hernia- 
like protuberances from the middle or lower portion of the body of the hydranths, there being but 
one to a hydranth. Although the hydranths bearing these bodies are usually apparently unmodified, 
they sometimes appear to be somewhat shrunken, as if impoverished by the growth of the gonophores. 
These latter show no trace of medusoid structure, either externally or in sections, and, what is more 
remarkable, there is no sign of anything like a blastostyle or spadix. Gonophores bearing ova, and 
others bearing spermatozoa, are found on the same colony. 
Distribution . — Station 3991, between Honolulu and Kauai Island, 296 fathoms, 
