193 
the anterior side; there are no musclefibres on the extra-pair of secondary mesenteries; the 
fibres are found on the anterior side of the anterior pair of secondary mesenteries and on the 
posterior side of the other mesenteries. They are absent (or not visible) on the posterior pair 
of sagittal primary mesenteries. The same system is found in all (4) the polyps of this 
species but one of the young polyps of PI. V, fig.. 1 had the lamellae on the primary trans¬ 
versal mesenteries on the anterior side of one mesentery and on the posterior side of the other 
mesentery of the same pair (fig. 258, /.) —- Through the curving of the oral cone and of the 
actinopharynx the direction of the mesogloeal lamellae is not to be made out immediately but 
since they are not visible in cross-sections of the oral cone, and only in oblique sections l am of 
opinion that these lamellae converge from the free border of the mesentery towards the top of 
the oral cone; at last they are subparallel with the actinopharyngeal wall, so that the muscle- 
fibres, which are found on these lamellae are longitudinal (cf. the schematical fig. 254). The 
other side of the mesenteries is entirely free from lamellae. — The primary transversal mesen¬ 
teries with their lower border are fixed to the interzooidal septum, near the polypar limit. 
Reproductive organs. Up till now the genital cells of the Antipatharia are found in the 
primary transversal mesenteries only and never in the other mesenteries. This Eucirripathes 
has well developed ovaria not only in the primary transversal mesenteries but in both anterior 
pairs of secondary mesenteries also. It is true that these ovaria are especially developed in the 
primary transversal mesenteries, to such a degree that they are extended S-shaped between body- 
wall and actinopharynx (PI. V, fig. 7), but the secondary mesenteries are so much broadened that 
the entire polyp is divided by the transversal mesenteries in very unequal parts: a large anterior 
one, and a much smaller posterior part since the posterior secondary mesenteries are sterile and 
require much less room. This fact, together with the presence of fertile secondary mesenteries, 
is easily to be distinguished in horizontal sections (PI. V, fig. 7) as well as in vertical sections 
(PI. V, fig. 4). In one polyp there were ova to be seen even in the anterior pair of sagittal 
mesenteries (PI. V, fig. 4) but the sections gave no absolute certainty on this head. The ovaria 
are found in the mesenteries, mentioned above, over their entire length, except in the extreme 
upper part of the oral cone. The ova do not deviate from those of the former Eucirripathes ; 
there is no egg-cone towards the entodermal surface. The mesenterial mesogloea may be followed 
for a little distance in the ovaria, without forming a clear mesogloeal capsule around the entire 
ovarium. The mesogloea is dissolved into very fine fibrillae, which surround each ovum with 
a thin capsule. The larger, ripe ova are found especially in the superficial parts of the ovaria, 
while the young ova are found in the deeper parts, especially near the visible part of the 
mesenterial mesogloea. In this case a connection of the egg-capsule with the mesogloea of the 
mesentery is often visible; usually these young ova are oval in shape, with their pointed side 
turned towards the mesogloea. The ova are situated unilaterally in the mesenteries; in PI. V, 
figs. 4 and 7 this is indicated by the course of the visible part of the mesenterial mesogloea, 
very near one of the surfaces of the mesentery (fig. 7: and v x ). The unchanged entoderm-cells 
contain pigment, but not in very great quantity. 
The mesenterial filaments are found not only along the free border of the transversal 
mesenteries but also along at least either anterior pair of secondary mesenteries, usually the 
25 
SIBOGA-EXPEDITIE XVII. 
