322 
THE VOYAGE OF H.M.S. CHALLENGER. 
The CBSophagus runs posteriorly and ventrally from the branchial sac, and after a 
short course opens into the small, ovate, and smooth-walled stomach (PI. XXXVIL 
tig. 8, st.). The stomach lies with its long axis dorso-ventrally. The intestine arises 
from its ventral end and soon turns anteriorly. It then curves round dorsally, and runs 
nearly parallel to the stomach and oesophagus (PL XXXVIL tig. 8, i.) until it reaches 
the dorsal edge of the body, where it terminates. The anus (PI. XXXVII. fig. 8, a) is 
nearer to the posterior than to the anterior end of the body, a point in which this species 
agrees with Pyrosoma and ditfers from all ordinary Compound Ascidians. It is obvious 
that very slight change would be required to convert this alimentary canal into one 
agreeing with that of Pyrosoma, both in structure and course. 
The intestine is occupied throughout the greater part of its length by a series of large 
dark coloured faecal pellets, which are always a conspicuous feature (PI. XXXVIL fig. 8). 
A system of branched tubules ramifies over the wall of the intestine in the middle part 
of its course. The various branches converge to a common duct, which leaves the wall 
of the intestine on its posterior edge opposite the stomach, and seems to open into 
the stomach, near its intestinal end. 
The vas deferens is the most conspicuous part of the reproductive system. It 
consists of a coiled part, which forms several spiral turns, and a terminal straight portion. 
Several pyriform spermatic vesicles are united by very delicate ducts to the inner end of 
the spiral portion of the vas deferens. The ova are small and inconspicuous. They are 
absent in the younger Ascidiozooids, and seem, to be formed late in life, and after the 
testes, so that there is here an approach to proterandry, a condition the reverse of that 
which I have found in most other Compound Ascidians, ' The ova form an elongated 
mass placed on the straight portion of the vas deferens. 
No embryos were found in the Ascidiozooids examined, but some tailed larvae of very 
large size are imbedded in the test near the closed end of the colony. They are of the 
ordinary shape, with an ellipsoidal body nearly 2 mm. in length, and a well-developed 
tail 4 mm, long. A single small pigmented sense-organ is present, and there are three 
large adhering papillae at the anterior end of the body. 
Family VII. Polystyelid^, n. fam. 
Colony massive or incrusting, sessile, rarely pedunculated, or formed of small 
masses connected by stolons. No common cloacal cavities present, 
Ascidiozooids large, usually short-bodied, rarely with a distinct abdomen. Both 
apertures four-lobed, and opening directly to the exterior. 
Test firm and cartilaginous. Matrix generally fibrillated, test cells small and 
inconspicuous, bladder cells rarely or never present. Vessels abundant, 
branched, and provided with distinct terminal bulbs. 
