184 
THE VOYAGE OF H.M.S. OHALLEHGEK. 
turhinatum each system forms a separate lobe in the form of a truncated cone projecting 
from the surface of the colony. 
The specimens described as Sidnyum turhinatum by Professor E. Forbes ^ and by 
Dr. Fleming ^ are, according to Alder, ^ not that species, but belong . to a separate but 
allied genus Parascidia, Milne-Edwards, characterised by an eight-lobed branchial aper- 
ture. Alder named them Parascidia forhesii and Parascidia jiemingii, and described a 
third species Parascidia Jlahellata. 
Sidnyum pallidum, n. sp. (PI. XXV. figs. 4-6). 
The Colony is of irregularly globular form, and is attached by a small area at the 
lower end. The upper surface of the colony is broad and rounded. There is no lateral 
compression. The surface is moderately even but not smooth. The colour is a pale but 
dull grey. 
The length is 1‘5 cm., the breadth is 1‘7 cm., and the thickness is 1’4 cm. 
The Ascidiozooids are of moderate size and fairly numerous ; they are arranged in 
systems around the common cloacal apertures, which are small but distinct. The body 
of the Ascidiozooid is long and narrow, being usually about 8 or 9 mm. in length and 
less than 1 mm. in breadth. It is of a very pale yellow colour and semi-transparent. 
The three regions of the body are clearly distinguishable. 
The Test is soft and flexible. It is of a light grey colour and is transparent. The 
test cells are small but numerous. There are no bladder cells present. 
The Mantle is thin and transparent. The musculature is feeble. The muscle bands 
are all longitudinal in direction ; they are narrow and not closely placed. 
The Branchial Sac is well developed. There are about twelve transverse vessels, all 
of the same size. The stigmata are small but well formed, and are regularly arranged. 
The Dorsal Lamina is represented by a series of short stout languets. 
The Alimentary Canal is relatively very long, and forms a narrow loop. The stomach 
is globular and has its wall irregularly thickened. 
The Post- Abdomen is long and less opaque than usual. It contains both male and 
female reproductive organs. 
Locality. — Off Marion Island, depth 50 to 75 fathoms. 
This species, although it resembles Morchellium giardiiasoraQ respects, is quite distinct 
from that and all previously described species both in external appearance and internal 
' British Mollusca, vol. i. p. 13, 1853. 
“ British Animals, p. 469, 1828. The specimen was found hy Dr. Fleming on the shores of the Isle of May in the 
Firth of Forth. 
® Ann. and Mag. Nat. Hist., ser. 3, vol. xi. p. 152, 1863. 
