300 DR. E. L. MOSS ON THE ANATOMY OF 
distance below the orifice, two clear circular cells lie symmetrically on either side of the 
endostyle (figs. 3 and 4, n). The heart lies between the stomach and the base of the 
appendix, and, contracting vermicularly, propels the blood at the rate of about 250 pul- 
sations a minute, in a broad stream over the surface of the testis, and in a still pulsating 
current through the appendix, down one side and up the other, in canals lyins on: either 
side of the muscular plane (figs. 1, 2, 3, and 5, A). | 
The nervous systems of both groups of Appendiculariæ present such similarities of 
structure and development, that a single description will suffice for both. The ganglion 
(figs. 1, 2, 3, 4, and 5, 1) is imbedded in a depression in the anterior paries of the 
branchial sac; a horseshoe-shaped are springs from its upper part, and gives origin to a 
pair of branches which encircle the orifice and supply its sphineter. Right and left, 
branches pass from: the lower extremity of the ganglion obliquely round the branchial 
chamber to the ciliated respiratory openings. The main trunk descends anterior to the 
pharynx, curves round between the lobes of the stomach, and divides into two delicate 
nerves, which passalong the appendix on either side of the central axis inside the muscular 
bands, and. exhibit alternate dilatations, increasing in size, at intervals which lessen, as 
they approach: the: tip (figs. 1, 2, 3, and 5, c). The muscular tissue supplied by these 
nerves is very finely and distinctly striated, with minute lacunæ between. its fibres, its 
general appearance being not unlike the muscular structure of the human heart.. 
In the second group of Appendicularie, the length of the body is increased by the sepa- 
ration of the branchial chamber from the viscera. by a stalk of considerable length. 
At the oral extremity a jug-like dilatation of the internal tunie contains the branchial. 
sac, with its two: postero-lateral ciliated respiratory openings, a minute and. shortened 
endostyle between and above these openings, and in the anterior wall a ganglion, with an. 
otolithe attached to its left side. 
The inhalant orifice possesses a broad sphincter, and is guarded. by six active tentacula. 
with bulbous bases. | 
A. closely ciliated pharyngeal tube forms the greater part of the stalk, and leads from 
the lower part of the branchial sac to the stomach. A second dilatation of the inner 
tunic, occupying the centre of the body, contains the heart and intestinal apparatus. 
The rectum terminates posteriorly and rather on the right side, close above the point of 
attachment of the appendix.. This organ projects from the centre of the body at a con- 
siderable angle, and is shaped like a cordate leaf, a peduncle and midrib being represented 
by the central axis, surrounded by muscular fibres spread out on either side in flat longi- 
tudinal bands. The lower half of the body is occupied by a globular mass of compressed 
yellow cells, and below them by a tapering ovary containing, in some specimens, upwards 
of 400 ova about z4; inch in diameter. 
In addition to the otolithe and oral tentacula, all the varieties of Appendicularia possess. 
an organ of sense analogous to that of Salpa and Doliolwm, in the form. of a pear-shaped 
ciliated sae (figs. 1, 2, 3, 7) lying to the right of and attached to the ganglion in nearly 
the position in which Gegenbaur has figured the unsymmetrical ciliated opening in his 
A. furcata. | | | : : da d 
I have lately captured a new short-bodied form in the warm surface-water of the 2 
