of high lamellae in the actinopharynx, just as in Stichopathes semiglabra , which in other 
respects is also very much like the species under consideration. 
The mesenteries are normal in number and course. The secondary mesenteries descend 
to a subequal level at the side of the bodywall and along the actinopharynx. The mesenterial 
system of longitudinal muscles is the same as in Stichopathes ceylonensis , except for the primary 
sagittal mesenteries, for which I was not able to make out a muscle-system. 
The mesenterial filaments are very strongly developed along all the primary mesen¬ 
teries, but not along the secondary ones. I hey are so much developed as to penetrate into 
the top of the tentacular lumen. I hey are single-lobed and without pigment. 
Reproductive organs. There are testes-vesiculae with a diameter of 70 \x ; • they are 
everywheie in the same stadium of ripeness. I he tails are crowded in bundles; the heads 
are arranged in longitudinal rows (PI. VII, fig. 4). They are found in the primary transversal 
mesenteries. It is remarkable that testes are also found in the entoderm of the bodywall 
near the places ot attachment of the transversal mesenteries (PI. VII, fig. 4), but also at a much 
farther distance from these mesenteries, even diametrically opposite the mesenteries. In this case 
there can be no question about an invagination as is the normal course of development in 
other species, since the mesogloea is much to thick to give in. The growth ot the testes makes 
the entoderm swell, as is shown in PI. VII, fig. 4, but a mesogloeal capsule, which is present, 
although very thin, in the normal testes, is absent of course. In the mesenteries the mesogloea 
is always very thin, so that an invagination is possible; usually the growth will take place 
towards the place of minor resistance. — 
Further it is remarkable that in one of the series testes are found in the ectoderm (!) of 
one of the tentacles (PI. VII, figs. 9 and 10). This vesicle is surrounded by a mesogloeal capsule 
(fig- 9 )- At first I thought about the possibility of the testes-vesicle being liberated through the 
mouth and secondarily reaching a flaw of the ectoderm, but PI. VII, fig. 9 shows clearly that the 
testes are lying in the ectoderm; below the testes the ectoderm has almost disappeared, while 
at the left it covers the vesicle. In one of the other sections (PI. VII, fig. 10) I saw that the 
mesogloea is interrupted below the vesicle and that some heads of spermatozoa project in the 
mesogloea and even in the entoderm. My opinion is that these testes have taken their origin in 
the entoderm of the tentacle, as is described above for the body wall-entoderm, but now very high 
in the tentacle, where the mesogloea is much thinner than in the bodywall. So it was possible for 
the mesogloea to invaginate towards the entodermal side so that the capsule got an ectodermal 
situation. It is true that in this case the mesogloea of the tentacle in PI. VII, fig. 10 ought to be 
connected with the mesogloeal capsule, but this could not be made out with certainty so that I 
omitted this connection. — I do not know any other way of explaining this strange situation. 
Parasites. In several polyps I found the same unicellular parasite as in Stichopathes 
saccula a. o. It is found in the entoderm of the bodywall near the connecting septum of the 
axis, The entoderm below the parasite has entirely disappeared, while the mesogloea is pressed 
outwards knob-shaped. This last fact is to be explained by the axis, which is almost in contact 
with the bodywall, resisting the inward growth of the parasite, which is much thicker than the 
entoderm. Ihe surface of the parasite does not show pseudopodial lobes. 
SIBOGA-EXPEDITIE XVII. 
30 
