114 MR. GOSSE ON A NEW FORM OF CORYNOID POLYPES. 
and remained nearly in contact with the Annelid's body, moving but slightly; but no 
sooner did it retire, than they began instantly to bow forward, and gesticulate as before. 
These movements were continued, so far as I observed, all the time that the Sabella was: 
retracted ; and were not in any degree dependent on currents in the surrounding water, 
whether produced by the action of the Annelid, or by other causes. They were not 
rhythmical; each individual appeared to be animated by a distinct volition. 
Applying a higher magnifying power than I had yet used, to the animals, I found that 
the head-lobe enclosed a central cavity ; that the arms were also hollow, with thick walls, 
marked with transverse lines (internal septa ?), and muricated on the exterior; and that 
the body contained an undefined sub-opake nucleus (see fig. b), doubtless a stomachal 
cavity. l ) dig 
I cut out with fine scissors a segment of the tube, including two of the parasites, with 
that portion of the network of threads that carried them. They were immediately 
paralysed by the division of the threads; but those that remained on the tube were 
unaffected by the violence. The hiatus in the continuity of the circle was healed in a 
day or two; not by the approach of the divided edges of the tube, but by the shooting of - 
the threads across the chasm. One of the animals thus cut out is represented (at d), as 
it appeared immediately after the excision, magnified 240 diameters. When subjected to 
the action of the compressorium, with a power of 560 diameters, the arms were seen to be 
formed of globose cells, made slightly polyhedral by mutual pressure, set in single series 
(fig. e). The interior of these organs was divided by septa, placed at intervals of about 
the diameter. Some, at least, of the cells contained a small bright excentric nucleus 
(fig. f). 
When the tissues were quite crushed down by the pressure of the compressorium, a 
quivering motion was visible among the disjointed granules; but it was very slight. No 
trace of cilia, nor any appearance of ciliary motion, was perceptible during life. 
This larger Sabella-tube was not the only one infested with the parasites. I observed 
them on two, at least, of the smaller specimens, in the same situation, and with precisely 
the same movements. The extremity of one of these smaller tubes I cut wholly off, and 
placed in the live-box of the microscope. Two of the parasites only were on it, which 
were active at first, but in about an hour—probably from the exhaustion of the oxygen 
in the small quantity of water enclosed—they decomposed, or rather disintegrated; the 
outline dissolving, and the external cells becoming loose and ragged, and the whole 
animal losing its definite form. | 
One of these specimens, however, while yet alive and active, afforded me an observation 
of value, I had already associated the form with the Hydroid Polypes, and was inclined 
to place it in the family Corynide, considering the arms to be tentacles, and the head- 
lobe to be homologous with them in character, but abnormal in form. It appeared to be 
a three-tentacled Coryne, with the tentacles simple instead of capitate. But while I was 
observing the individual in question, I saw it suddenly open the head-lobe, and unfold it 
A een - a broad shovel-shaped expanded disk; not however flat, but with the 
pd ^m quts ng towards each other, like two leaves of a half-opened book (fig. 9). 
i; y reminded me of the great sucking-disk, which I had seen evolved from 
