188 
THE VOYAGE OF H.M.S. CHALLENGER. 
Polyclinum pyriformis, n. sp. (PL XXVI. figs. 1-4). 
The Colony is pyriform and is attached by a short stalk formed by a prolongation 
of the narrower end of the colony. The upper end is wide and rounded. There is little 
or no lateral compression. The surface is regular and smooth. The colour is a light 
greyish-yellow. 
The length is 3 cm. (of which 8 mm. is formed by the stalk), the breadth is 2 ‘2 cm., 
and the thickness is about 1’7 cm. 
The Ascidiozooids are large and very numerous ; they are arranged in systems around 
the common cloacal apertures, of which there are several on the upper surface of the 
colony. The Ascidiozooid is usually about 12 mm. in length and 1*5 mm. in breadth. 
The body is distinctly divided into three regions. 
The Test is soft and gelatinous in the upper part of the colony ; it becomes firmer on 
the peduncle. It is of a light grey colour and very transparent. The test cells are small 
and not very numerous ; they are usually triangular or stellate, and frequently have 
long branched prolongations. There are no bladder cells. 
The Mantle is thin and transparent. The musculature is rather weak, and is mainly 
longitudinal in direction. 
The Branchial Sac is large and well developed. The transverse vessels are all of the 
same size. The stigmata are long and narrow, and are arranged with regularity. 
The Endostyle is long and narrow but conspicuous. 
The Dorsal Lamina is represented by a series of languets. 
The Tentacles are large and closely placed; there are about twelve of them, all of the 
same size. 
The Alimentary Canal forms a short wide loop. The stomach is large and its wall is 
smooth. 
The Post- Abdomen is long but narrow. 
Locality. — Kerguelen Island; depth, 10 to 60 fathoms. 
This species has a certain external resemblance to Amaroucium globosum, which was 
obtained at the same locality on the shores of Kerguelen Island. The two species are, 
however, quite distinct, although allied forms. There are two specimens of Polyclinum 
pyriformis in the collection, and both are very distinctly pear-shaped and shortly 
pedunculated (PI. XXVI. fig. 1). The dimensions given in the above description are 
those of the large specimen. The smaller one is 2'3 cm. in length (including peduncle), 
1'3 cm. in breadth, and IT cm. in greatest thickness. 
The yellow colour of this species is due mainly to the abundance of the Ascidiozooids, 
which are of an opaque yellow colour and very distinctly visible through the transparent 
test. The Ascidiozooids are arranged in fairly regular circular systems (PI. XXVI. 
