AGLAOPHENIA CONSTRICTA. AT 
Aglaophema bispinosa is a beautiful species, and is surpassed in size by 
very few hydroids. The proximal part of the stem is composed of a 
congeries of tubes (Pl. XXVII.), which at rather regular intervals become 
curiously contorted into knot-like projections, and which, at the extreme 
proximal end, become separated from one another, and here form a large 
entangled mass of hydrorhizal filaments. Knot-like projections of quite a 
similar kind occur in the European Aglaophenia myriophylla. Towards its 
distal extremity the stem loses its polysiphoniec or fascicled condition and 
becomes monosiphonic. In the specimens examined the pinne were borne 
along somewhat less than the distal half of the stem. 
The hydrothece are remarkable for the long, strong tooth which 
projects from the front of the margin; but a still more remarkable 
character is found in the presence of a second mesial nematophore 
situated on the internode, just behind the normal one and unconnected 
with the hydrotheca. (PI. XXVIII.) 
The corbule (Fig. 3) are very beautiful. They closely resemble those of 
A. distans, present the same elements in their formation, and, like these, 
afford a most instructive illustration of the essential morphology of the 
organ. The peduncle which connects them with the common stem, and 
which consists of the proximal portion of the pinna, which, in its ter- 
minal portion, becomes transformed into the corbula, is unusually long 
(Fig. 4), and consists of five scarcely altered internodes with their hy- 
drothece ; an additional mesial nematophore, however, is developed near 
the proximal end of each of these internodes. 
Aglaophenia constricta. 
Pl. XXIX. Figs. 1-4. 
Trophosome.— Stem attaining a height of about eight inches, thick, 
fascicled, springing from an entangled mass of wiry filaments, and send- 
ing off numerous, irregularly disposed, simple branches, which carry 
alternately disposed pinne, three pinne springing from every internode. 
Hydrothecze with the distal half expanded and separated from the proxi- 
mal part by a deep constriction; margin with four broad teeth. Supra- 
calycine nematophores slightly overtopping the margin of the hydro- 
theca; mesial nematophore nearly equalling in length the height of 
the hydrotheca, to which it is almost entirely adnate; cauline nema- 
