244 
THE VOYAGE OF H.M.S. CHALLENGER. 
The oesophagus is long and narrow, and runs posteriorly to open into the large 
quadrate stomach. The walls of the stomach are moderately thick and are thrown into 
a few slight longitudinal folds. The intestine is long and thin walled. It runs posteriorly 
from the stomach for a considerable distance and then turns abruptly to the dorsal edge 
and anteriorly so as to form a narrow loop. The rectum is very like the intestine. In 
some cases it is wide, when distended with food matter. The anus is placed behind 
the middle of the branchial sac, usually about two-thirds of the way down from the 
anterior end. It is a small aperture with a thickened and reflected margin. 
The spermatic vesicles are globular in form. The vas deferens is not so large and 
conspicuous as is usual amongst Compound Ascidians. In several of the Ascidiozooids 
examined mature ova were found in the peribranchial cavity, usually very far forward,, 
close to the branchial aperture, but no embryos or larvae were seen. 
Psammaplidium suhviride, n. sp. (PI. XXXI. figs. 5-10). 
The Colony has an irregularly rounded or ovate form. It is attached by the 
lower end and is not compressed laterally. The surface is, even but is slightly roughened 
all over. The colour is a pale opaque greenish-grey. 
The length is 2'5 cm., the breadth is 1‘3 cm.,, and the thickness is 1 cm. 
The Ascidiozooids are rather small but numerous. They are scattered evenly all 
over the surface, and are not arranged in systems. They lie at right angles to the 
surface of the colony, but their bodies are usually not much elongated. 
The Test is hard and firm. It contains great quantities of imbedded sand grains in 
all parts. Where free from impurities it is clear and transparent, and is of a pale grey 
colour. The test cells are abundant. They are mostly of rounded form and have 
granular protoplasm. No bladder cells are present. 
The Mantle is thin and its musculature is feeble. The narrow muscle bands run 
longitudinally. 
The Branchial Sac is well developed. The transverse vessels are wide. The stigmata 
are narrow and exceedingly long. The ciliated cells are rounded and not very 
conspicuous. 
The Endostyle is wide. Its course is undulating. 
The Dorsal Lamina is represented by a series of short horn- like languets. 
The Alimentary Canal forms a long and very narrow loop. The stomach is small 
but the intestine is large. 
The Post- Abdomen is very variable in size. It is always narrow. It contains both 
male and female reproductive organs. 
Locality. — Station 142, December 18, 1873; lat. 35° 4' S., long. 18° 37' W.; 
depth, 150 fathoms; bottom, green sand; bottom temperature, 47° F. 
