REPORT ON THE HYDROIDA. 7 
Nematophores in the Statoplea. 
a. Hydrocladial nematophores.—These are arranged in two sets on every internode 
of the hydrocladium, and consist of an azygous or mesial nematophore and a pair of lateral 
nematophores. The mesial nematophore is in the form of a tubular process springing 
from a point of the hydrotheca-bearing internode immediately below the hydrotheca, to 
the front wall of which it becomes in almost every instance adnate for a greater or less 
extent of its length. Ina very few cases the mesial nematophore of the Statoplean 
Plumularide, while fixed immovably by its base, remains free for the rest of its course, 
having no adhesion to the hydrotheca (Pl. XVI. figs 1-3). In a single instance (Aglao- 
phenia bispinosa of the Gulf Stream Report’) a second mesial nematophore is developed 
in a longitudinal line behind the first. 
The mesial nematophore communicates through its base with the cavity of the inter- 
node, just below the hydrotheca. In that portion of it which is adnate to the front of 
the hydrotheca it communicates by means of a longitudinal sht-hke aperture with the 
cavity of the latter. It is always open at its distal extremity, where an aperture, usually 
very oblique, allows of the projection of its protoplasmic contents im the form of free 
pseudopodia. Besides the terminal and the longitudinal slit-like aperture there is also in 
many cases an aperture on its inner or hydrothecal side (Pl. XV.), just beyond the point 
where its distal portion becomes free from the walls of the hydrotheca. Occasionally an 
imperfect transverse septum exists in some part of its course (Pl. XX. figs. 4, 5). 
The mesial nematophore is in a few cases adnate to the walls of the hydrotheca for its 
entire length. In most cases, however, its distal extremity is continued for some distance 
as a free process. This free distal portion of the mesial nematophore varies much in 
length. In Aglaophenia proper it is generally quite short, but in some other genera it 
attains a great length, being developed in the form of a long curved horn (Pl; VEE). 
The lateral nematophores in the Statoplea are tubular, cup-shaped, or crescentic bodies, 
always two in number, situated symmetrically one on either side of the hydrotheca, nearly 
on a level with its orifice or thecostome. They spring from the hydrothecal internode 
with the cavity of which they communicate by their base. They terminate distally by 
been described by G. O. Sars (loc. cit. p. 112, pl. iv. fig. 10) as developed below the hydrothece in his Halecitwm 
gorgonoide. 
Mr. Busk, in a letter which I have recently had from him, describes from a specimen in his collection but from 
an unknown locality a Hydroid whose affinities are with the Sertularide rather than with the Plumularide, and which 
yet carries on the front of every hydrotheca a small sessile nematophore-like body. Whether this is to be regarded as 
a true nematophore or not, can scarcely be asserted with confidence from the examination of a dried specimen. Its 
peculiar position, lying as it does on the front wall of the hydrotheca, without any apparently direct communication with 
the hydrocaulus, is certainly against placing it in the same category with the true nematophores. The Hydroid is also 
very exceptional in other respects, and Mr. Busk regards it as the type of a new genus, for which he proposes the name 
of Greeneia. 
1 Hydroids of the Gulf Stream, p. 46, pls. xxvii. xxviii. 
