REPORT ON" THE TUNICATA. 
413 
tr and usually placed alternately, as seen in the figure. No narrow horizontal 
membranes were noticed. 
It is impossible to say with certainty whether this specimen should be described as a 
new species or referred to Polycarpa longisiphonica. I prefer to take the latter course 
until more specimens have been examined, and it has been determined whether or not 
that species has a wide range of variation. 
The specimen measures 3 '8 cm. in length and 2 *2 cm. in greatest breadth. It was 
obtained at Station 162, April 2, 1874 ; lat. 39° 10' 30" S., long. 146° 37' 0' E.; depth, 
38 fathoms ; bottom, sand and shells. 
Polycarpa bassi, n. sp. (PI. XLIX. figs. 1-3)* 
External Appearance . — The body is oblong in outline, and somewhat compressed 
laterally. The posterior end is rounded, and the area of attachment is on its left side. 
The anterior end is broad and truncated, it runs obliquely forwards and ventrally. The 
dorsal and ventral edges are nearly straight and parallel, the body being of much the same 
breadth all the way down. The apertures are placed rather far apart, at the ventral 
and dorsal extremities of the long anterior end of the body. They are sessile and 
not conspicuous. The branchial is more anterior than the atrial. The surface is uneven 
and rough, being marked with prominent ridges and grooves, which are chiefly longitudinal, 
and having here and there sand grains and a few shell fragments attached. The colour 
is a dark ruddy brown. 
The length of the body is 4 '4 cm., the greatest breadth of the body is 3 cm., and the 
thickness is 1*8 cm. 
The Test is thin but tough. 
The Mantle is very thick, but the musculature is only slightly developed. 
The Branchial Sac is strong and rather coarse. It is long and curved with the con- 
cavity dorsal. It has four large folds upon each side. The internal longitudinal bars are 
wide and ribbon-like. There are five or six upon each fold, and two or three only in the 
interspace. The meshes are much elongated transversely and rather irregular ; each 
contains about twelve stigmata. The transverse vessels are all of much the same size ; 
occasional smaller ones are present for short distances. 
The Dorsal Lamina is narrow, and is a perfectly plain membrane with neither ribs 
nor teeth. 
The Tentacles are large and simple ; there are about thirty. 
The Dorsal Tubercle is elliptical in outline, and is prominent though not large. It 
lies in a deep triangular peritubercular area, and the horns, which are turned inwards, 
form two closely placed spirals, each having several turns. The aperture is directed 
posteriorly, and the longer axis of the tubercle is transverse. 
