412 
THE TOYAGE OE H.M.S, CHALLET!^GER. 
meshes are elongated vertically, and contain each three to five stigmata, which are rather 
wider than the vessels between them. Muscle fibres are present in the transverse vessels. 
The Tentacles are few in number but rather long. 
Locality. — Station 246, July 2, 1875 ; lat, 36° 10' Ni long., 178° O'E. ; depth, 2050 
fathoms^ bottom, Globigerina ooze ; bottom t-emperature, 35°'l F. 
This species, although very small, is evidently adult, since the genital gland was found 
to contain masses of large and mature ova. There is nothing noticeable about the external 
appearance (PI. XLIX. fig. 7) of the single specimen. It might almost pass for a rather 
wrinkled and shabby looking individual of Styela grossularia of. our own coasts, and yet 
it was obtained from a depth of over 2000 fathoms in the centre of the North Pacific 
Ocean. 
The branchial sac (PI. XLIX. fig. 8) is very brittle, but exhibits none of the pecu- 
liarities found in the case of some other deep-sea Ascidians. The stigmata are regular, 
and of the ordinary size. Cilia are present and have the usual arrangement, and no 
spicules are found in the vessels. 
Polycarpa longisiphonica {?), Ilerdman (PI. XLIX. figs. 4-6). 
Polycarpa longisiplionica, Her dm an, Report upon Challenger Tunicata, parti, p. 177, pi. xxiii. 
figs. 3-6. 
This single specimen of Polycarpa, from Station 162, resembles Polycarpa longi- 
siphonica in most particulars, but is rather different in external appearance. It is 
especially deficient in the characteristic from which that species derives its name, as the 
present specimen has the apertures sessile, though large and distinct (see PI. XLIX. fig. 
4), while in Polycarpa longisiphonica ^ they are placed upon the summits of singularly 
long projections. Then, again, the anterior extremity in this specimen is wide, while in 
Polycarpa 'longisiphonica it is narrow as compared with the rest of the body. The 
specimens of Polycarpa longisiphonica formerly described were either free or only very 
slightly attached, while the present specimen is attached to the interior of a LameUibranch 
shell by a large part of its left side (PL XLIX. fig. 4). In the present specimen the lobes 
of the apertures are very much larger than those in the specimens from Port Jackson. 
Notwithstanding all this -external difference, the branchial sac of the present 
specimen (PI. XLIX. fig. 5) is extremely like that of Polycarpa longisiphonica."^ 
Figure 5 on Plate XLIX. shows a fold and a complete interspace formed 
of six rows of meshes, each more or less square in shape, and containing four 
to six stigmata very regularly arranged. The fold shown (hr./.) has nine internal 
longitudinal bars, the next one had eight. The transverse vessels are of .three sizes (see 
1 See this Report, part i. pi. xxiii. fig. 3. 
^ See this Report, part i. ,pl. xxiii. fig. 4. 
