MR. HUXLEY ON THE ANATOMY OF SALPA AND PYROSOMA. 
571 
raentary lacteal system, a means of straining- off the nutritive juices from the stomach 
into the blood by which these vessels are bathed ? 
The intestine is connected with the parietes of the sinus in which it lies by in- 
numerable delicate short threads, like a fine areolar tissue. 
14. In Salpa A, the only other organ contained in the circum-visceral sinus, be- 
sides the intestine and “ system of tubes,” is a mass of clear cells (ce), rendered poly- 
gonal by mutual pressure, and placed at the upper and back part of the sinus ; to 
this body the name of eleeoblast” has been given by Krohn. It has by some authors 
been confounded with a liver, an organ to which it certainly has no analogy what- 
ever. The eleeoblast is much larger and more conspicuous in the young than in the 
adult Salpce^ and frequently, but not always, its cells contain an oily matter. 
There would seem to be no clue either to the homology or to the function of this 
eleeoblast. Without hazarding a conjecture, it may be remarked, as a curious fact, 
that these animals, so remarkable for possessing in the foetal state a true thougli 
rudimentary placental circulation, possess an organ which in structure and duration 
somewhat calls to mind the thymus gland. 
15. The nervous system consists of a single subspherical ganglion (d), situated in 
the space between the inner and outer tunics, just where the anterior and lower ex- 
tremity of the hypopharyngeal band joins the ventral paries. It gives off" two delicate 
branches forward to the “languet” (16.), and a great many in all directions to the 
parietes of the body. There were no branches traceable specially to the mouth or 
towards the oesophagus. 
A delicate but strong vesicle attached to the anterior and lower surface of the 
ganglion, and containing four subhemispherical calcareous bodies, with black pigment 
spots on their outer surface, evidently represents the auditory vesicle and its otolithes 
in the gasteropod and acephalous Mollusca: and a conical depression in the outer 
tunic leading towards this auditory vesicle, would appear to be intended to bring it 
into closer relation with the surrounding medium, Plate XVI. fig. 5. 
16. There would appear to be yet another organ of special sense, composed of the 
“languet” {/) and the “ciliated fossa” (w), called by Eschricht the “langliches 
organ.” 
The “languet” (Plate XVI. fig. 5) is a long tongue-shaped or conical process, fixed 
by its base to the ventral surface of the respiratory cavity where this is joined by the 
anterior extremity of the gill, and for the rest of its extent floating freely in the re- 
spiratory cavity : it is curved so as to be convex anteriorly and concave posteriorly, 
and its anterior surface is marked by a shallow vertical groove; at the base this 
groove is wider, and where it becomes continuous with the surface of the respiratory 
cavity, it presents a narrow median slit, which leads into a small purse-shaped 
’ cavity, flattened from side to side and richly ciliated within, Plate XVI. fig. 5 w. 
The posterior contour of this ciliated fossa is formed by a delicate thickened band 
or filament, much more distinct in some other species than in the present. 
