41G 
THE VaYAGE OF H.M.S. CHALLEJ^GER. 
Family Ascidiida:. 
To this group belong two' species, of which one {dona aspem, n. sp.) was collected 
during the Challenger Expedition at Japan, while the other [Ascidia scahra {?), 0. F. 
Muller) was dredged during the cruise of the “ Porcupine ” off the coast of Ireland. 
Ascidia scahra (•^), 0. F, Muller (PL XL VII, fig. 11)*, 
One specimen, which probably belongs to this species, was obtained during the first 
cruise of the “Porcupine,” in the summer of 1869, off the coast of Galway, at lat. 
53° 10' N. and long. 9° 19' W., from a depth of 15 to 20 fathoms. It is about l‘5-cm. in 
length, and differs from typical examples of Ascidia scahra in having an extraordinarily 
long atrial siphon (PL XLVII. fig. 11 , at), about 5 mm. in length. The surface of the 
test is smooth. 
The brancliial sac is in rather bad condition, and the internal longitudinal bars are 
ver}^ narrow. There are no papillae. In other respects the specimen agrees fairly well 
vdth ordinary British specimens of Ascidia scahra. 
dona aspera, n. sp. (PL XLIX. figs. 11-13). 
External Appearance. — The general shape is irregularly cubical, and the body is not 
compressed laterally. The anterior extremity is truncated and much corrugated. The 
posterior end is wide and evenly rounded, there being no adhering prolongations of the 
test in this region. The body is attached to an Annelid tube near the middle of each 
side. The apertures are both anterior, being placed close together near the centre of the 
truncated anterior extremity ; they are much contracted. The surface is very irregular, 
and is covered with short sharp-pointed projections, which are especially developed at 
the posterior end. The colour is light grey. 
The length of the body is 1‘5 cm., the breadth is IT cm. 
The Test is thin and transparent except at the points of attachment on the right 
and left sides, and at the anterior end where it is irregularly thickened. 
The Mantle is very muscular on the anterior part of the body, and moderately so 
along the dorsal and ventral edges and round the posterior end. It is thin and almost 
destitute of muscles on the posterior parts of the two sides. The sphincters around the 
apertures are strong, and from under them, upon each side of the body, spring five 
powerful longitudinal muscle bands. 
The Branchial Sac is moderately strong. The transverse vessels are all of much the 
same size, and are rather wide. The internal longitudinal bars are strong and bear stout 
papillae at the angles of the meshes, and also intermediate ones. The latter are joined, 
like the chief papillaa, by delicate horizontal membranes which divide the meshes 
