42 THE VOYAGE OF H.M.S. CHALLENGER. 
Lytocarpus secundus, Kirchen. (Pl. XTV.). 
Aglaophenia (section Lytocarpia) secunda, Kirchenpauer, Abhandl. aus dem Gebiete der Natur- 
wiss. von dem naturwiss, Verein in Hamburg, Band v. 1872. 
Lrophosome.—Colony attaining a height of more than two and a half feet; main stem 
3 
fascicled, rooted by an entangled mass of fibres, and emitting, along nearly its entire length, 
short branches which carry the hydrocladia, and which, though regularly disposed in alter- 
nate pinne, are all directed towards the same side of the stem; hydrocladia: about two- 
tenths of an inch in length. Hydrothecee rather deep, with crenate margin ; hydrothecal 
ridge short and broad, situated near the base of the hydrotheca; mesial nematophore adnate 
to the hydrotheca walls for about two-thirds of the height of the walls, and terminating 
as a short, free, blunt spine, which does not reach the level of the hydrotheca margin ; 
lateral nematophores thick, spout-shaped processes not overtopping the hydrotheca. 
Gonosome.—Phylactocarps replacing the hydrocladia at short intervals along the 
hydrocladia-bearing branches, each consisting of a jointed rachis, supporting on every 
alternate internode a long curved spine, which carries from its base to its apex a double 
series of wide cup-shaped nematophores, similar nematophores being also borne by the 
rachis. 
No gonangia were present in the specimens. 
Lytocarpus secundus is a remarkable and beautiful Hydroid, rendered very striking by 
‘its large size, and by its regularly disposed primary branches. These are each about 
two inches in length, and though at their origin given off as pinne from opposite sides of 
the stem, become all directed towards one side, thus giving a secund character to the 
ramification. In some of the larger specimens a few branches are given off irregularly 
towards the base of the stem. 
Another very striking feature is found in the curious comb-like phylactocarps. These 
are shorter than the hydrocladia, generally about half their length, and their rachis, like 
that of the hydrocladia, consists of a consecutive series of nearly equal internodes, which 
in the phylactocarp are about eighteen or twenty in number. From the same side of 
every alternate internode there is sent off a short thick process which supports the long 
shghtly curved spine, the spines thus carried in a single series along the rachis giving to 
the phylactocarp its resemblance to a comb. Large regularly disposed cup-shaped 
nematophores are arranged from the base to the apex of the spine in two alternate or 
sub-opposite series. The spine is itself hollow, with a terminal orifice. Nematophores 
entirely similar to those of the spine are scattered over the rachis. 
Though no gonangia were developed in the specimens, I take it for granted that the 
comb-like organs are true phylactocarps. The spine-like appendages (the teeth of the 
comb) are probably the representatives of the mesial nematophores of suppressed 
hydrothece. 
