REPORT THE TU^HCATA. 
299 
The colonies are of irregular shape (see PI. XLI. fig. 1, where A. represents the 
present species), and are not so rounded as those of Leptoclinum carpenteri (PL XLI. 
fig. 1, B.). They are also flatter and more spreading, of a slightly whiter colour, and 
much harder and firmer, and not so smooth to the touch, consequently there is no 
difficulty in distinguishing the two species even by their external characters only. The 
Ascidiozooids also are clearly visible in the present species, which is not the case in 
Leptoclinum carpenteri (see PI. XLI. fig. 1, A. and B.). The branchial apertures lie in 
minute depressions which are closely placed all over the surface of the colony. 
The colonies are of various sizes, from a few millimetres to 2 centimetres in length. 
They are all attached to parts of the Alga, around which they have grown so as to 
completely imbed it. The surface of the colony feels hard and slightly rough, but no 
projections are visible. Vertical sections show (see PI. XLI. fig. 5) that as in the case 
of Leptoclinum carpenteri the superficial layer is formed of test containing no calcareous 
spicules. 
The Ascidiozooids as a general rule are placed at right angles to the surface of the 
colony, but in some cases they are inclined at an angle to it. The abdomen is sometimes 
not directly posterior to the thorax, but is bent upwards so as to lie partially on its dorsal 
edge (PI. XLI. fig. 5, right hand side). 
The test is, relatively to the size of the colony, not so large in amount as in the case 
of Jjeptoclinum carpenteri. It has the characteristic Leptoclinid stifi’ness and opacity. 
The test cells are inconsjncuous, but the spicules are very abundant (see PL XLI. figs. 5, 7). 
In some places they are even more numerous than is represented in figure 5. A feAV 
bladder cells are present in the outer part of the test in some places. The spicules are 
very regular. The rays are usually wide at the base, and curve gently upwards to the 
pointed apex (see PL XLI. fig. 6). Rarely an irregadar spicule is seen like one of those 
.shown in figure 6, where one ray is larger than the others. In some cases the rays are 
narrower than usual, and the apices are much sharper. 
A vertical section through the colony (PL XLI. fig. 5) shows that below the su])erficial 
layer composed of test only (t.m.), occurs a Avide zone (sp.) in wliicli the spicules are 
closely placed. This region surrounds the greater part of the thorax of the Ascidiozooids. 
It varies somewhat in width, but is always considerably wider than the corresponding 
zone in Leptoclinum carpenteri. In the deeper parts of the colony spicules are present 
in the test, but they are not very numerous and are scattered evenly. 
The muscles of the mantle are well developed and run in various directions (PL XLI. 
fig. .5). The branchial siphon is large, and the test lining it contains spicules (PL XLI. 
fig. 5, hr.). The sphincter is Avell developed, and from its posterior edge two bands of 
muscle fibres arise on each side, one near the dorsal and the other near the ventral edge 
of the siphon. These muscle bands run posteriorly over the surface of the thorax, and 
soon join (see PL XLI. fig. 7) to form a single band which continues to run backwards 
