312 PROFESSOR W. A. HERDMAN ON THE 
thin, leathery, raised at intervals to form little pointed tubercles, the larger of which 
are echinated (fig. 5). Mantle muscular, with regular circular and longitudinal bands. 
Branchial Sac with four large folds on each side. There are six to nine bars on a fold, 
and four in the interspace. Dorsal lamina a broad plain membrane. There are about 
thirty very long simple tentacles and some intermediate smaller ones. The dorsal 
tubercle has both horns coiled inwards to form short spirals (fig. 8). There are two or 
three long gonads on each side, and many endocarps. Fig. 7 shows the arrangement 
of the alimentary canal. 
In the smaller, more globular specimens the conical spiny tubercles on the test are — 
relatively more numerous and more closely and regularly placed (see figs. 2, 3, 4, and 6), 
The Challenger specimen figured, from Kerguelen, was intermediate in size to the 
larger and the smaller Scotia examples, and was smoother in character of test. 
Styela paesslert, Michaeisen. (Plate, figs. 12 to 14.) 
This species was described by MicHar.sEn in 1900 from specimens obtained in the — 
Straits of Magellan. The Scotea specimens from the Falkland Islands seem to be 
rather larger on the whole, but agree in essential characters. _ 
The following description, from the Scotea material, may be useful :—There are 
about twenty specimens, varying in size from 1 cm. to 3 em. in length by 1°5 cm. in 
average breadth, obtained from Station 118, at the Falklands, depth 6 fathoms; and a 
couple from Port Stanley, February 2, 1904, 6 fathoms. 
The colour varies from a creamy white to a yellowish brown, and the surface of the 
test is in most places closely wrinkled. The branchial sac has four folds on each side, 
the largest being those adjacent to the dorsal lamina, with ten bars each, while the others 
have usually six bars. Fig. 12 gives the plan of both sides of the branchial sac as seen 
in section, with the number of bars and of rows of stigmata shown by the figures. The 
folds have from five to ten bars, and there are from two to five (usually four) bars in the — 
spaces between. These numbers agree fairly well with those given by MICHABELSEN. 
The transverse vessels are of three sizes arranged with regularity : 1—3—2—3—1, and { 
having a narrow horizontal membrane in addition crossing the meshes (fig. 13). Most 
of the meshes are square, with five to seven stigmata in each. The extreme dorsal and 
ventral meshes are more elongated transversely, and contain a greater number of stigmata. 
The dorsal tubercle is of curious form (fig. 14), a simple crescent with the horns 
anterior and having a globular excrescence in the concavity. The dorsal lamina is a 
plain membrane. The tentacles are crowded and number about a hundred. They are 
of two sizes, roughly fifty of each. MicHarLsEN records only sixty tentacles, but as 
the specimens he examined were smaller than ours, the difference need not be regarded 
as important. . 
Although some of the above characters do not agree precisely with those given by. 
MicuaxExsen, still the differences are not, I think, greater than what may reasonably e 
