ACALEPH/E. 
213 
°f things by comparison, and have taken our ideas of animal life from 
the larger animals ; and an animal which we cut and turn inside out, 
which we cut again, and it still hears itself well, gives one a singular 
s hock. How many facts are ignored, which will come one day to 
derange our ideas of subjects which we think we understand ! At 
present we just know enough to he aware that we should he surprised 
a t nothing.” 
Notwithstanding the philosophic serenity which Bennet recommends, 
the fact of new individuals resulting from dividing these fresh-water 
P°lypes was always a subject of profound astonishment, and of never- 
ending meditation. 
Sektulaeiada;. 
All Hydraidse, with the exception of the Hydra and a few other 
8 e nera, arc marine productions, varying from a few lines to upwards 
°t a foot in height, attaching themselves to rocks, shells, seaweeds, 
ail <l corallines, and to various species of shell-fish. Many of them 
attach themselves indiscriminately to the nearest object, hut others 
s how a decided preference. Thuiuria thrya attaches itself to old bi- 
valves; Thoa hdlecuia prefers the larger univalves; Antennularia 
a ntenninu attaches itself to coarse sand on rocks; Laomedea geni- 
e ulata delights in the broad frond of the tangle ; Plwwhria oatherina 
attaches itself in deep water to old shells, corallines, and ascidians, 
growing in a manner calculated to puzzle the naturalist, as it did 
^rahbe, the poet, who writes of it : 
“ Involved in sea-wrack, here you find a race 
Which science, doubting, knows not where to place ; 
On shell or stone is dropp’d the embryo seed, 
And quickly vegetates a vital breed.” 
® er tularia pumilct, on the other hand, loves the commoner and coarser 
wracks. “The choice,” says Dr. Johnston, “may in part he dependent 
their habits, for such as are destined to live in shallow water, or on 
a s hore exposed by the reflux of every tide, are, in general, vegetable 
phrasites ; while the species which spring up in deep seas must select 
J(i tween rocks, corallines, or shells.” There seems to he a seioct'oD 
6Ven a s to the position on the rocks. According to Lamouroux, some 
P°b'picrs always occupy the southern slopes, and never that towards 
