778 The Siphonophores. [ October, 
| EINE sn 
We their native element, when the combined 
SKS movements of different series of bells im- 
IK >) part a spiral motion to the whole colony. 
ga tc: zu Ch In truth, the grace of this animal is some- 
Wo AN , ' S 
eases eal S thing marvelous, and when once seen is 
eS. not soon to be forgotten. 
wR There are two genera of Physophores 
GRY closely resembling Agalma in external 
Barras HN shape, but so well marked that they are. 
commonly placed in different genera. They 
are known as Agalmopsis, and Halistem- 
ma. The likeness of the former of these 
animals to Agalma, as its name betrays, 
is very great (Fig. 121), The most import- 
- ant difference between the two is in the 
. structure of the tentacular-knobs, which in 
\ Agalmopsis (Fig. 13) have but a single ter- 
minal filament, while in Agalma, as has 
‘ra 
rh 
i 
| 
ay f 
u (TN been already pointed out, there are two 
YAN of these terminal _fila- i 
e- i wf ments and an interme- 
diate vesicle. In minor 
details also, as in the po- 
sition of the sexual-bells 
SSE: 
we 
~ 
i, 
(af BEN 
/ if NaN \ upon the base of the 
{ a) NS) A\ “tasters,” instead of mid- 
f i \ sal as b He 
i /ax| \N' way between the feeding- 
ty aN hy\ polyps on the stem, 
mK & 
= 
a, 
' Agalmopsis differs from 
Agalma, but as has been 
already said, the general 
outline of the two is much 
the same. 
pF 
(3 
gE. 
— 
Bien 
We: 
‘ x } The genus called Hal- 
\ \ istemma, or “ sea-tube,” 
) N approaches very closely, 
) iY in form, the type Agal- 
\ ma. The great difference ; 
: between the two, as be- Pendant 
fe Fic. 13- ig 
Fic. 12,—Agalmopsis. tween Agalmopsis and nob of Agen : 
a 52 and 13 are copied from my paper in the Bull, Mus. Comp. Zool., V0 
0. 7. 
