MR. HUXLEY ON THE ANATOMY OF SALPA AND PYROSOMA. 
583 
edges with small teeth ; they project anteriorly and posteriorly beyond the vertical 
bars. 
Both systems of bars appeared to be tubular, although no corpuscles were seen 
moving in them, and the edges of the vertical sinus were thickly covered with long 
cilia, moving in opposite directions on the opposite sides. 
51. The dorsal edges of the two branchiae were separated by a space containing 
the thickened dorsal folds already mentioned, and this is continuous posteriorly with 
a band which connects the mouth with the dorsal surface of the respiratory cavity, 
and allows the water to pass back on each side of it to the post-branchial cavity. 
52. Anteriorly on the ventral side is an organ (fig. \0w) analogous to the “ ciliated 
fossa ” of the Salpce, and behind this a series of tongue-shaped eminences (fig. 1 f) 
projects into the respiratory cavity, analogous to the “ languet” of the Salpce. 
The “ ciliated fossa” is compressed laterally, and placed upon the upper surface of 
a protuberance, formed by the ventral wall of the respiratory cavity in the middle 
line. On each side a flattened ciliated band (fig. 10 x) runs up on the respiratory 
wall in front of the anterior edge of the branchiae, and meets above with its fellow 
of the opposite side. 
The “languets” are altogether eight in number. They extend in a longitudinal 
series between the ciliated fossa and the mouth. They are all slightly excavated and 
ciliated anteriorly. 
53. Immediately beneath the ciliated fossa, and in the midst of the ventral sinus, 
lies the ganglion. This is about xie^th of an inch long, somewhat egg-shaped, with 
its large end forwards. Its posterior extremity is in contact with a mass of deep red 
otolithes, fig. 10 c?. 
A small nerve runs from the ganglion lo the lateral ciliated band. Five or six 
branches are distributed to the anterior aperture, and two principal branches run 
backwards to the posterior aperture, giving off branches to the mouth in their 
course. 
54. The Pyrosomata are hermaphrodite. 
The testis {p) is the so-called hepatic organ ” of Lesueur, Savignv and Peron. 
It consists of ten, twelve, or more ceeca, connected by their posterior extremities, and 
here joining a central duct, which opens by a papilla at the upper and posterior part 
of the respiratory cavity. The spermatic sacs lie loosely in a dilatation of the vascular 
sinus, and are bathed freely by the blood. 
Each sac is delicate and thin-walled, about y^th of an inch in diameter, and very 
variable in length. In adult specimens the distal or anterior end of each sac is filled 
with a pale cellular mass. Towards the attached end this becomes darker and more 
distinctly granulous, and the filiform bodies of masses of spermatozoa are plainly 
perceived. 
The spermatozoa have narrow elongated heads and very long delicate tails. 
55. There cannot be said to be any ovary properly so called. But to the left, and 
4 F 2 
