•210 
THE VOYAGE OF H.M.S. CHALLENGER. 
and sometimes also the dorsal ends of each row the stigmata rapidly become smaller, 
leaving the transverse vessels with wide triangular ends (PL XXVJII, fig. 3, sg'.), as in 
Distaplia (compare PL XVIII. fig. 3). The languets along the dorsal line of the sac 
are large triangular flaps flattened antero-posteriorly (PL XXVIII. fig. 4, 1.). In some 
cases the stigmata extend in an uninterrupted series across the dorsal line. The 
endostyle is conspicuous and has an undulating course. 
The alimentary canal is rather large, but the loop it forms is remarkably short 
(PL XXVIII. fig. 2, i.). The oesophagus leaves the dorsal edge of the posterior end of the 
branchial sac and runs for a short distance backwards. The stomach lies on the dorsal edge 
of the abdomen. It is short and wide, and its wall is thrown into a series of longitudinal 
folds (PL XXVIII. fig. 2, St.). The intestine, which is wide and thin-walled throughout, 
leaves the posterior end of the stomach and turns at once ventfally and then anteriorly. 
(3n reaching the level of the front of the stomach it crosses to the dorsal edge of the 
abdomen, passing over the left side of the oesophagus, and then turns anteriorly to become 
the rather short wide rectum which runs along the dorsal edge of the thorax (PL XXVIII. 
fig. 2, r.). The intestinal loop is wide and forms the ventral part of the abdomen. The’ 
intestine and rectum are filled with dark coloured faecal matter in their entire length. 
The post-abdomen is short and wide (PL XXVIII. fig. 2,y>. ah.). It contains both male 
and female reproductive organs, the ova being placed at the anterior end, while the 
spermatic vesicles occupy the remainder of the region. The mature ova are large and of a 
bright yellow colour. The vas deferens is usually conspicuous. Some of the Ascidio- 
zooids examined contained several large tailed larvae' in the peribranchial cavity. The 
body of the larva is of nearly globular form, and has two pigmented sense-organs. 
Aplidium despectum, n. sp. (PL XXVIII. figs. 11-13). 
The Colony is an irregular mass consisting of two rounded pieces connected by a 
narrow neck. It was attached by a small area at one end. The surface is irregular but 
fairly smooth. The colour is a pale brownish-grey. 
Tlie length is about 2 cm., the greatest breadth 1'3 cm., and the thickness 0’5 cm. 
The Ascidiozooids are small, and appear to be placed quite irregularly. No systems' 
and no common cloacal apertures are visible. 
The Test is firm and cartilaginous. It is of a dull grey colour and nearly opaque. 
The clear matrix is crowded with large test cells, mostly of rounded form and with 
granular contents. Some of them are slightly pigmented. No bladder cells are present. 
llie Mantle is moderately thick, but not very muscular. It is rather opaque. 
The Branchial Sac is small and opaque. The stigmata are minute ovate slits placed! 
rather far apart. 
Tli/i Post- Abdomen is short and opaque. 
