596 
MR. HUXLEY ON DOLIOLUM AND APPENDICULARIA. 
80. The animal has an ovoid or flask like body, Plate XVIII. fig. 1, one-sixth to one- 
fourth of an inch in length, to which is attached a long curved lanceolate appendage or 
tail, by whose powerful vibratory motions it is rapidly propelled through the water. 
The body frequently appears wrinkled and crumpled externally, and its upper, 
smaller extremity has rarely clear and well-defined edges. The lower part of the 
body is frequently separated from the upper by a slight cleft or constriction, fig. 4, 
and it is here that Mertens places the orifice of the mouth, supposing indeed that 
the upper part of the body plays the part of a maxilla ! 
81. The smaller extremity of the animal is perforated by a wide aperture {d) which 
leads into a chamber, which occupies the greater part of the body, and at the bottom 
of this chamber is the mouth. The chamber answers to the respiratory cavity of the 
Tunicata, and is lined by an inner tunic distinct from the outer ; the space between 
these, as in the Salpoe, being occupied by the sinus system. 
On the side to which the caudal appendage is attached, an endostyle (c), altogether 
similar to that of the Salpce, lies between the inner and outer tunics ; and opposite to 
this, or on the. ventral side, close to the respiratory aperture, there is a nervous 
ganglion, to which is attached a very distinct spherical auditory sac, containing a 
single, also spherical, otolithe. The sac is about 2 -^th of an inch in diameter. The 
otolithe about figs. 1, 2, 4 a. 
Anteriorly, a nerve is given off from the ganglion {a) which becomes lost about the 
parietes of the respiratory aperture ; another large trunk passes backwards {h) over 
the left side of the oesophagus, and between the lobes of the stomach, until it reaches 
the appendage, along the axis of which it runs, giving off filaments in its course, 
fig. 2. I did not observe anything resembling the “languet” of the Salpce; but 
Mertens describes two leaf-like larninse existing, one on each side of a “semicylin- 
drical” body, which seems to be the nervous ganglion. 
82. There is no proper branchia ; but that organ seems to be represented by a 
richly ciliated band or fold (e) of the inner tunic, which extends from the opening of 
the mouth forwards, along the ventral surface of the respiratory cavity, to nearly as far 
as the ganglion ; when it divides into two branches, one of which passes up on each 
side, so as to encircle the cavity {/). This circlet evidently represents the ciliated 
band” of Salpa. 
The mouth (g) is wide, and situated at the posterior part of the ventral paries of 
the respiratory chamber. The oesophagus (h) short, and slightly curved, opens into 
a wide stomach {i) curved transversely, so as to present two lobes posteriorly. 
Between the two lobes, posteriorly, the intestine (k) commences, and passing up- 
wards (or forwards) terminates on the dorsal surface just in front of the insertion of 
the caudal appendage (/). 
The heart lies behind, between the lobes of the stomach. I saw no corpuscles, and 
the incessant jerking motion of the attached end of the caudal appendage rendered 
it very difficult to make quite sure even of the heart’s existence. 
