414 THE VOYAGE OF H.M.S. CHALLENGER. 
Locality. — Station 162, April 2, 1874 ; lat. 39° 10' 30" S., long. 146° 37' 0" E.; 
depth, 38 fathoms ; bottom, sand and shells. 
This is an ordinary Polycarpa with well-marked family and generic characters, hut 
apparently distinct from any previously described species. The single specimen was 
obtained in Bass’ Straits, from a depth of 38 fathoms. The external form (PI. XLIX. 
fig. 1) is not remarkable. It has a leathery Cynthiad test corrugated and somewhat 
incrusted externally, and having inconspicuous apertures with no weU-marked lobes. 
The mantle is remarkably thick (see PL XLIX. fig. 3), but is of a firm gelatinous consist- 
ency, and has comparatively few muscle bands. 
The coarse branchial sac, although long, is rather narrow, and so leaves a considerable 
cloaca on the dorsal edge in which the rectum lies (PI. XLIX. fig. 3). The transverse 
vessels in the branchial sac are irregular, occasionally branching or uniting. They are 
supplied with muscle fibres, some of which are continued into the interstigmatic 
vessels (PL XLIX. fig. 2). 
The dorsal tubercle is distinctly Cynthiad in its appearance, and resembles that 
of Cynthia cerebriformis, Herdman, where, however, the aperture is lateral, not posterior. 
The endostyle is very prominent. 
The alimentary canal is long and narrow. The cesophagms starts from the dorsal 
edge of the posterior end of the branchial sac, and runs almost directly ventrally, with 
merely a slight backward inclination, round the posterior end of the peribranchial cavity, 
and is attached to the inner surface of the left side of the mantle. There seems to be no 
marked dilatation representing the stomach (see PL XLIX. fig. 3), the oesophagus and 
intestine being directly continuous ; towards the ventral edge of the posterior end the 
intestine turns anteriorly, then dorsally, and then somewhat posteriorly again, so as to form 
three-fourths of a circle. This open intestinal loop encloses a pale grey homogeneous 
looking soft mass (see PL XLIX. fig. 3), which is clearly the structure erroneously 
described as the ovary by Savigny in his Cynthia mytiligera} and afterwards shown by 
R. Hertwig ^ to be merely a thickened fold of the lining membrane of the peribranchial 
space. The intestine finally runs to the dorsal edge of the body, and turns anteriorly to 
become the long narrow rectum, which may be traced along the dorsal edge nearly to the 
atrial aperture (PL XLIX. fig. 3). The polycarps are very numerous, and are found on 
both sides of the body imbedded in the mantle. Their short narrow ducts are all directed 
towards the atrial aperture (see PL XLIX. fig. 3). 
This species is allied to Polycarpa mytiligera, Savigny,^ but is readily distinguished 
from it by the external form, the absence of the stomach, and the condition of the dorsal 
tubercle. 
1 M^moires, p. 98, pi. viii. fig. 2^. 
2 Beitrage zur Keimtniss des Baues der Ascidien, Jenaische Zeitschr., Bd. vii. p. 81. 
^ M^moires, p. 158, pi. viii. fig. 2. 
