EEPORT ON THE TUNICATA. 
279 
the spiciile seems to be built up of a number of short wedges or cones joined by their 
apices, and having the bases prolonged into tapering raysd 
The muscle bands in the mantle are delicate but very numerous. They run longi- 
tudinally, transversely, and irregularly, and form a close network over the thorax. The 
branchial siphon is very large, in some cases nearly as large as the branchial sac. It is 
lined by test containing a number of spicules (PL XXXIY. fig. 9, hr.). The branchial 
sphincter is large, and it gives rise at its posterior edge to a strong retractor muscle 
on each side, which runs backwards over the thorax near the dorsal edge, and, after 
joining a smaller muscle band from the mantle in the neighbourhood of the posterior 
extremity of the endostyle, runs outwards into the test for a considerable distance. This 
retractor muscle is, when in the test, a tubular prolongation of the mantle ; it may be 
regarded as a vascular appendage from the Ascidiozooid, in the walls of which muscle 
fibres have been developed. 
The branchial sac is a small ovate organ (PL XXXIV. fig. 9) with rather thick walls 
and small stigmata. The endostyle is especially large. The dorsal languets are long, 
and are tentacular in shape ; there is one on each transverse vessel. The tentacles are 
rather larger than is usual in the Didemnidse (see PL XXXIV. fig. 13). There are eight 
larger and eight smaller placed alternately. 
The oesophagus leads directly backwards from the posterior end of the small branchial 
sac to the rather large stomach (PL XXXIV. fig. 9). The shape of the stomach is 
ellipsoidal, and its outer wall is smooth. Several longitudinal thickenings formed of 
long columnar cells project into the lumen. The intestine is very similar in appearance 
and course to that of Leptoclinum speciosum. 
The testis is large, and lies alongside the intestinal loop. The vas deferens is 
conspicuous ; it commences by coiling from eight to ten times sjm’aUy around the testis 
(PL XXXIV. fig. 9). 
Two small cylindrical colonies of this species were obtained at Station 142 near the 
Cape of Good Hope, from a depth of 150 fathoms. They are exactly like the elongated 
forms of Leptoclinum speciosum, -vnr. asp)crum from Bahia (figured in PL XXXVI. fig. 9), 
in all respects except that the surface is perfectly smooth. The Ascidiozooids seem, 
however, to be rather more numerous and more closely placed than in Leptoclinum 
speciosum. The spicules vary a good deal in size, but resemble those of that species 
and its variety. These specimens from Station 142 seem to be in an intermediate 
condition between Leptoclinum speciosum and the variety asperum, and show therefore 
that the two forms cannot be regarded as distinct species. 
1 In this respect they resemble the spicules of some Alcyonaria, such as Sarcodictyon and Alcyonium. The simple 
spicules, formed of 1, 2, 3, or 4 pieces only, found in Sarcodictyon (see Herdman, On the Structure of Sarcodictyon, Proc. 
Boy. Phys. Soc. Edin., voL viii. p. 31, 1884) never seem to occur in the Leptoclinids. 
