234 AMPHITRITE. 
tions of an active plume, hence it is restraimed when the plume is defec- 
tive; and the body declining while simple increment of the branchie 
advances, an unmeasurable disparity between them may follow. 
In the natural state, mere survivance seems productive of new parts 
towards either extremity, and all in their proper order. But such a re- 
generation as above described is then precluded, for two plumes cannot 
subsist in a single tube ; nor can the same body have more than one. 
If the animal be sundered, each portion regains the defective parts. The 
two terminal glandular papillsee were recognised very distinctly as repro- 
duced by the larger portion losing the fragment. The tube being cur- 
tailed below, a second time exposed them on the 6th of October, then, 
however, adhesion scarcely followed, and the tenant forsaking it entirely, 
perished within a week. 
A disordered plume always indicates disease ; protrusion from the 
orifice is unfavourable ; and the Amphitrite seems to abandon its dwell- 
ing to die. 
No creatures are more dependent on the quality of their proper 
element. When denied frequent renewal they retreat far from view, 
and remain in pertinacious concealment, becoming altogether enfeebled, 
while the symmetrical arrangement of the plume is impaired. Yet after 
a month’s interval, so great is the benefit from a recent supply, that in 
half an hour they endeavour to resume their wonted functions. 
I have never obtained the progeny of the Amphitrite directly from 
the parent, which precludes me from treating of the fertility of the one, 
or of the earliest aspect of the other. Very small tubes are usually soli- 
tary. Once, however, a group exceeding twenty, occurred within limits 
not greater than the circumference of a shilling, which indicated a quan- 
tity of spawn or ova as having issued from one individual. The tubes, from 
an inch and a half to three inches high, were connected by extraneous 
matter. We have already described the appearance and operations of 
some very minute specimens on the Campanularia (Sertularia) dichotoma. 
Specimens have survived above a year in confinement. One, very 
small, seated on a Sertularia, was preserved in the purest water, the Ser- 
tularia having been the principal object of observation. Nevertheless 
