EEPORT OX THE TUXICATA. 
411 
The test is strong and tough and quite opaque. It is, however, rather thin except at 
the posterior end. It is white on section. 
The mantle is very thick, and has imbedded in it large pale genital glands, which 
from their number and appearance might almost be considered as polycarps. 
The branchial sac is strong. There are four folds upon each side, and they seem to 
vary somewhat in size, two or three being large, as in Styela radicosa, and the rest much 
slighter. The branchial sac in other characters (PI. XLIX. fig. 10) resembles that of 
Styela radicosa {cf. PI. XXIY. fig. 7, in the First Part of the Eeport). The internal 
lonoitudinal bars are broad and ribbon-like. The transverse vessels are all of about the 
O 
same size, with the exception of the occasional much wider ones (PI. XLIX. fig. 10 , tr.). 
In some places the sac is very irregular. The figure given shows four rows of stigmata 
passing first into three then into two and finally into one at the edge of the fold (hr./.). 
The tentacles are large. The branchial aperture is so much invaginated (probably 
through sudden and extreme contraction) as to fiU up the branchial siphon and cover 
completely the prebranchial zone and the bases of the tentacles. The dorsal tubercle is 
in the same condition as in Styela radicosa. 
In a case like the present one, where a species was described from a single specimen 
and then another specimen turns up afterwards which differs somewhat from the first, it 
is very difficult to decide whether the two should be united or considered distinct species. 
I think it best, taking into consideration what we know as to individual variation in 
Ascidians, to refer the present species to Styela radicosa, at least until some other 
specimens are found which will throw light upon the affinities of the two forms. This 
specimen was obtained at Station 1G3 d, June 12, 1874, Twofold Bay, Australia; lat. 
33° 57' 30" S., long. 151° 39' 15" E. ; depth, 120 fathoms; bottom, green sand. 
Styela pusilla, n. sp. (PI. XLIX. figs. 7, 8). 
External Appearance. — The body is dome-shaped or almost hemispherical. The 
posterior end forms the wide base of attachment, and has a slightly expanded margin. 
The anterior end is convex, and the sides are alike. The apertures are both anterior, 
not distant, and very inconspicuous. The surface is minutely wrinkled all over so as to 
give it a roughened appearance. The colour is an earthy brown. 
The length of the body is 4 rnm., the greatest breadth of the body is 6 mm. 
The Test is moderately thick and rather tough. It is quite opaque. The inner 
surface is smooth, and of a bluish-white colour. 
The Mantle is yellow in colour, and has the musculature well developed. It is 
attached to the test closely at the apertures only. The bundles of muscle fibres form a 
close but fine network. The sphincters are strong. 
The Branchial Sac has several folds upon each side. The transverse vessels are 
moderately wide and all alike. The internal longitudinal bars are not very stout. The 
