REPORT ON THE TUNICATA. 171 



same number more distantly placed in the interspaces. The transverse vessels are all 

 much about the same size, and most of them have wide horizontal membranes hanging 

 from their inner edges (PL XXI. figs. 4 and 5, tr. and A.m.). The meshes are square 

 or a little elongated transversely, are often divided by delicate horizontal membranes 

 (PI. XXI. fig. 5, h.m.), and contain four or five stigmata each. The endostyle is well 

 marked and may be seen distinctly running to the base of the long sac. 



The tentacles are simple and are not long. They are of three sizes, placed usually 

 with several of the smaller ones between each pair of larger ones (PI. XXI. fig. 

 6, tn.). 



The dorsal tubercle (PL XXI. fig. 6, d.t.) is large and prominent, and each horn forms 

 a spiral ; the right one is large and is turned inwards, while the left is much smaller and 

 coils outwards. The peritubercular area is shallow and symmetrical. Both polycarps 

 and endocarps are very numerous. 



About a dozen specimens of Polycarpa tinctor were obtained at Port Jackson, at 

 depths varying from 2 to 15 fathoms. 



Polycarpa minuta, Herdman (PL XXII. figs. 1-4). 



Polycarpa minuta, Herdman, Prelim. Eep., Proc. Roy. Soe. Eilin., 1880-81, p. 78. 



External Appearance. — This species is dome-shaped, or nearly hemispherical ; the 

 anterior end is convex, and the posterior is wide, flattened, attached, and slightly expanded 

 at the margin. The apertures are both anterior ; they are not distant, and are sessile but 

 distinct. 



The surface is perfectly smooth and even. The colour is pale-yellowish brown. 



Length of the body, 0'6 cm.; breadth of the body, 0'9 cm. 



The Test is thin, but tough and strong. 



The Mantle adheres closely to the test, and is very thin. 



The Branchial Sac has four folds upon each side. The transverse vessels are all of 

 the same size. The internal longitudinal bars are very few, there being only two between 

 each pair of folds. The meshes are transversely elongated, and contain each six to eight 

 stigmata. 



The Dorsal Lamina is a plain membrane. 



The Tentacles are numerous and filiform. 



This is a very small species of Poh/carpa, and is rather like Styela grossularia, van 

 Peneden, in general appearance. It forms a small blister-like prominence on the stone to 

 which it adheres (PL XXII. fig. 1), is perfectly smooth on the surface, and of a yellowish- 

 brown colour. The apertures are placed close together at the anterior end. The test and 

 the mantle are both very thin, and adhere together closelv. 



The branchial sac (PL XXIL fig. 2) has the folds in the rudimentary condition which 



(ZUOL. CUAI.L. EXF. — FART XVII. — 1882.) J; '_'.'> 



