CATALOGUE OF TUNICATA. 39 



number on each fold. Every 6th transverse vessel very wide. Meshes 

 transversely elongated. About 6 or 8 stigmata in each mesh. Arrange- 

 ment of transverse vessels very irregular in places. 



Dorsal lamina a plain-edged membrane. 



Tentacles, 24 in number, simple ; of different sizes but not arranged 

 symmetrically ; some very long. 



Dorsal tubercle prominent, and circular in outline ; slit varying from 

 two simple spirals to a much convoluted condition or several distinct 

 apertures. 



Locality. Port Jackson ; five specimens. Port Stephen ; three 

 specimens. 



This large and irregular Styela (PI. Cyn. XIII., fig. 1) has very much 

 the appearance of a Microcosmus. The colour, texture, and encrusted 

 condition of the test all remind one of that genus ; but it is in structure a 

 true Styela. The form, test, mantle, tentacles, and branchial sac are 

 fairly constant in all the specimens. The dorsal tubercle, however, is 

 rather variable, although in all cases it is a large hemispherical promin- 

 ence. Figs. 3 to 7 show the exact form of the slit in several of the 

 specimens. A regular part of the branchial sac is shown in fig. 2 ; 

 some parts are, however, rather irregular, and there are wide vessels 

 running in several directions on the back. In some places there may be 

 as many as 10 bars on a fold and the same number in the interspace. 

 Occasionally a few of the tentacles may be larger than the rest, and 

 attain to a length of 1 cm. A considerable number of Amphipod Crus- 

 tacea were present in the branchial sacs of most of the specimens. 



At the posterior end of the body the mantle is prolonged into several 

 short ragged tags, which are received into irregular crypts in the 

 thickened basal part of the test. 



The alimentary canal is rather short and wide (fig. 8). The stomach 

 is raised on its inner surface into longitudinally running ridges. In the 

 loop between the stomach and the intestine lies an irregular pad of 

 gelatinous connective tissue. The anus is wide and has a plain 

 margin. 



There is a single large, rounded reproductive mass (fig. 8, r.<j.; /._//.) on 

 each side of the body. That on the right side is absent, or very slightly 

 developed in most of the specimens. There is a short oviduct, and either 

 one or several (see fig. 8, l.y.) more slender sperm -ducts leading from 

 each reproductive mass. 



I have associated this species with the name of the present Curator of 

 the Australian Museum, Mr. B. Etheridgc, junr. 



