CATALOGUE OP TUNICATA. 37 



Tentacles simple, unbranched. 



Alimentary canal with a well-marked stomach, and no distinct 

 glandular caecum or " liver." 



Gonads in the form of one or a few elongated tubes, or a large number 

 of small scattered masses (" polycarps ") attached to the inner surface of 

 the mantle. 



Only the two more ordinary genera of this sub-family, Styela and 

 Polycarpa, are represented in the collection. Both are apparently 

 common in the Australian seas. 



Styela, MacLeay, 1824. 

 This genus is represented by 6 species, 5 of which are new to science. 



Styela pinguis, n. sp., PI. Cyn. XII., figs. 110. 



External appearance. Shape elongate ovate, compressed laterally, 

 adhering by posterior third of left side. Apertures both on dorsal edge, 

 branchial at anterior end, atrial one-third of the way back ; both distinctly 

 4-lobed, but sessile. Surface smooth, but marked by slight branching 

 grooves. Colour dirty white. Length 5 cm., greatest breadth 3 cm., 

 thickness 2 cm. 



Test leathery, but soft on the surface, moderately thick and tough, 

 smooth and glistening on the inner surface. Matrix clear, but crowded 

 with very small test cells. Numerous small vessels with globular 

 terminal knobs ; some of the vessels are convoluted or spiral. 



Mantle yellowish brown, rather thin, but fairly muscular. Muscle 

 bundles very thin, forming a close network. 



Branchial sac with 4 distinct but rather distant folds on each side. 

 About 9 internal longitudinal bars on a fold and 6 in the interspace. 

 Transverse vessels of two sizes placed alternately. Meshes square, 

 containing each about 8 stigmata, and divided transversely by a narrow 

 horizontal membrane, which rarely interrupts the stigmata. Occasional 

 extra, partial, horizontal membranes are also present. The stigmata 

 are large, and regularly placed. A good many muscle fibres in the 

 larger transverse vessels. 



Endostyle very long, but not conspicuous. 



Dorsal lamina very inconspicuous. A narrow membrane with a 

 corrugated edge forming slight teeth. 



Dorsal tubercle ovate in outline. Both horns turned inwards and 

 slightly coiled. 



Tentacles long and slender, about 16 in number. 



