126 
THE VOYAGE OF H.M.S. CHALLENGEE. 
and is opaque. When split open or sectionised it is seen to have a very large number 
(varying from twenty-five to forty in the various stomachs examined) of folds in its 
interior (see PL XVI. fig. 15). These folds are not very prominent, but are closely placed : 
they run longitudinally, but are not continued over the entire length of the organ. 
They frequently branch, and new folds commence at various points, thus producing 
undulations in the course of the neighbouring ones. Figure 15 represents not a surface 
view of the folds, but an optical section, obtained by focussing down a little from the 
inner surface. In this way the columnar cells wdiich form the folds are seen in profile; 
gr. indicates the groove between two folds, and fd. the centre of a fold. 
The stomach opens on the dorsal side of its posterior end into a very short piece of 
narrow intestine, which at once dilates into a large globular cavity, forming the posterior 
and dorsal part of the visceral mass (PI. XVI. fig. 11). This is continued at its anterior 
extremity into a small funnel-shaped piece of intestine, which, after a slight constriction, 
opens into the long rectum. This part of the tube is narrow at its commencement, and 
runs anteriorly and slightly ventrally to reach the oesophagus. It then runs straight 
forwards, swelling slightly as it goes, and finally terminates in the anus, which is placed 
at the base of the atrial siphon (PI. XVI. fig. 11 , at.). The anterior part of the rectum 
is very large, and is usually distended with dark-coloured faecal matter. Viewed as a 
whole, the alimentary canal is remarkable for its large size and for the irregularity in its 
calibre. The intestine lies throughout its entire course on the dorsal side of the stomach. 
All the Ascidiozooids examined were hermaphrodite, there being one or two large ova 
along with the spermatic vesicles (PI. XVI. figs. 9, 11). The latter (PL XVI. fig. 11 , t.v.) 
stain more deeply with picrocarmine than the ova, and are large, opaque ovate bodies, 
placed in groups on the side of the intestine, and projecting beyond it on the dorsal edge 
and posteriorly. Each Ascidiozooid has a large bunch of from six to twelve vesicles 
(PL XVI. fig. 16, t.v.). The delicate ducts from the vesicles join at the base of the 
long and wide vas deferens, which is a conspicuous object running alongside the rectum 
throughout its entire length. 
Distaplia, Della Valle. 
DistapUa, Della Valle, Enove Contribuzioni alia storia naturale dejle Ascidie Composte, &c.. 
Reale Accademia del Lincei, 1880-81, p. 18. 
Distaplia, von Drasche, Die Synascidien der Bucbt von Eovigno, Wien, 1883, p. 22. 
Colony in the form of lobed masses or club-shaped knobs. 
Systems distinct, each one forming a knob or lobe of the colony. 
Ascidiozooids elongated antero-posteriorly, and placed vertically in the colony. 
Branchial aperture six-lobed. Atrial aperture provided with a languet. 
Test gelatinous, penetrated by ectodermal prolongations from the Ascidiozooids. 
