i6 
D. C. Danielssen. 
[No. i, 
The longitudinal muscles, which pass along both sides of the 
septa, are about uniform in breadth over the whole (Pl. III fig. 2), 
but towards the gullet-tube and intestinal canal they, as it were, 
collect more together, and give off strong muscular bundles which 
accompany the insertions of the septa on the digestive apparatus 
(Pl. II fig. 7 d, Pl. III fig. 1 c). Here they operate as 12 special longi- 
tudinal muscles that assist in shortening the gullet-tube and in- 
testinal canal. 
But besides the 12 septa which divide the en tire cavity of the 
body into 12 closed longitudinal chambers, there is seen, on the 
exterior wall of the gullet-tube and intestinal canal, between each 
two septa, a collection of fillet-formed prominences which issue 
from the connective-tissue of the digestive-apparatus (Pl. III fig. i d, 
2 b), are formed by the connective-tissue, and clad with rather 
short ciiiating cylinder-cells (PL III fig. 1 e). These prominences 
extend pretty far into the chamber; indeed, in the posterior part 
of the chamber they extend almost to the wall of the body; they 
are pretty firm, and sometimes divide themselves bifurcately, without 
however losing anything of their special character (Pl. III fig. 1 f). 
I have called attention to a similar relation in Fenja mirabilis, 
but in that animal they are not nearly so prominent. I do not 
know with what to compare these peculiar prominences, unless it 
be with undeveloped, imperfect septa, such as are sometimes met 
with in Actinidæ, but it must be remembered, always issuing from 
the wall of the body. Here, as has been shown, they issue from 
the gullet-tube and intestinal canal, and have no other histological 
structure than the one spoken of. It has not been possible, for 
me, to discover muscles on these organs, which, so far as I can 
make out, can have no other function than to divide the chambers 
in such a manner that a far larger belt arises with which the nu- 
tritory fluids may come in contact. No correspondent connection 
between them and the channel of the intestine exists, as there is 
a very broad connective-tissue layer sharply defining those parts 
from each other. 
The connective-tissue of the gullet-tube and the intestine is 
very broad, strongly fibrillous, and rich in connective-tissue corp- 
uscles and nutritory ducts; and upon its exterior surface, longitu- 
dinal and transversal muscles are found. From the inner surface 
of this connective-tissue, thick, long, prolongations issue, which 
extend into the channels of the gullet and intestine and form the 
large folds which are here observed (Pl. III fig. 1 g). These 
