6 W. A. HERDMAN. 
or less square and funnel-like when the animal is alive and fully expanded. The 
other anatomical characters are sufficiently shown in the figures on Plate I or 
described in the above diagnosis. 
STYELA ROTUNDA. 
(Plate VI., figs. 14-19). 
Locality.—Winter Quarters, in McMurdo Bay. 
External Appearance.—Shape almost globular, attached by a wide posterior end, 
not flattened. Both apertures minute, cross-slit, inconspicuous, sessile, on the rounded 
anterior end about 1 cm. apart. Surface even, but finely roughened. Colour yellow. 
Size 2 cm. dorso-ventrally x 1°8 cm. antero-posteriorly x 1°8 cm. from side to side. 
Test thin, but leathery ; stiff, but not tough, easily torn. 
Mantle closely adhering to inner surface of test. 
Branchial Sac with four folds on each side, the ventral ones are the slighter and 
placed further apart. Very many longitudinal bars are present. There may be as 
many as eight or ten on a fold, and about twenty to twenty-four in the interspace 
(fig. 15). The transverse vessels are of three orders, but none are very wide. The 
meshes are elongated vertically and contain two or three long narrow stigmata each. 
They are crossed by a fine horizontal vessel (fig. 15). 
Dorsal Lamina a narrow plain membrane. 
Tentacles, simple, at least forty large and a few smaller scattered irregularly 
between. 
Dorsal Tubercle simple, horse-shoe shaped, turned with the opening to one side. 
The Alimentary Canal is posterior to and partly on the left side of the branchial 
sac. The stomach is long and is very finely ridged along its length (fig. 17). 
The Gonads are two or three narrow, yellow, convoluted tubes on each side. 
This species recalls in some respects the species of Dendrodoa from Arctic seas, 
and especially perhaps D. kuekenthali, Hartmeyer, but differs in having gonads on 
both sides of the body—a character which determines its position as a Styela. It 
resembles in external appearance St. nordenskjoeldi, Michaelsen, from Magellan Strait 
and other localities at the south end of America, but differs wholly in the structure of 
the branchial sac and other details of anatomy. The figure (Plate VI., fig. 14) is from 
a photograph, and represents the specimen, of which the measurements are given above, 
at double the natural size. A second specimen slightly smaller, 1:8 x 1°6 cm., was 
obtained from ‘‘ Dredge off Coulman Island—13. i. 02—100 fathoms.” 
