242 
The second group contains Stick, gracilis ( VI) and Euant. longibrachiata (X), both with 
a complete system on all the mesenteries. This system is as follows: the longitudinal 
musclefibres are found on the anterior side of the posterior pair of 
secondary mesenteries and of the posterior sagittal pair, but on the 
posterior side of the other three pairs of mesenteries. 
It is to be remarked that by changing the position of the longitudinal musclefibres of 
the. first group towards 'the opposite side of the mesenteries and by inverting the entire figure, 
we get the system of the second group. The supposition would be apert that I have taken 
in VI and A' the transversal musclefibres for the longitudinal ones, but, although locally such 
an error is not impossible through the peculiar course of the mesenteries and the musclefibres, 
this is without any doubt not the case here. The system could be made out without any diffi¬ 
culty with these species in the series of sections, since it is very clear and regular in all the 
examined polyps. Besides in such a case I ought to have found the longitudinal fibres also, 
which are always better developed than the transversal fibres; but I saw no other system 
besides the one described. From the remaining systems ( III and VII) Eucirr. musculosa , 
with great probability, may be joined to the first group of Stick, ceylonensis a. o. •, the argu¬ 
ments for this opinion are given, in a more explicit manner, in the anatomical description of 
Eucirr. musculosa (cf. p. 199). — At last the system of Stick, saccula ( VII) \ this system 
deviates from the first group in the position of the longitudinal musclefibres on the posterior 
pair of secondary mesenteries. This system may be reckoned as a variant of the first group, 
so demonstrating the plasticity of the Antipatharia, even on this head. — While some species 
(. Aphan. Sibogae , Aphan. indistincta a. o.) have mesogloeal lamellae, with [Euant. dichotoma) 
or without musclefibres, on their primary transversal mesenteries only, an other species {Euant. 
ericoides) shows these lamellae, without fibres, on the same mesenteries, but on the anterior 
side of the anterior pair of secondaries besides, so following the system of the first group. — 
The probability is very great that we may take the longitudinal musclesy stem 
on the mesenteries of the first group as typical for the Antipatharia 
(cf. fig. 262, VIII, and the description on p. 241). 
This system may be substituted by the second system with reversed position of the 
musclefibres on all the mesenteries. Small deviations may occur. However there are several 
species without any trace of a mesenterial musclesystem. The longitudinal musclefibres are best 
developed in the primary transversal mesenteries; they are followed in strength by the secon¬ 
dary mesenteries, which are subequal, compared with each other. These fibres are very slight 
in the primary sagittal mesenteries, where I could see them clearly only very seldom. The 
sixth pair of secondary mesenteries did not contain musclefibres. 
The mesogloeal lamellae, which support the fibres, may be fused basally into small 
groups. -— One species only had a unilateral swelling of the primary sagittal mesenteries, 
but without lamellae or musclefibres. — In the lower part of the mesenteries (especially the 
primary transversal ones) the longitudinal musclefibres and the transversal ones on the oppo¬ 
site side of the mesentery, are almost parallel with each other, and with the free border of 
the mesentery. 
