CATALOGUE OF TUNICATA. 51 



it is quite possible that these minute specimens, on the average about 

 3 mm. in diameter, are the young of some other species of Polycarpa, or 

 even Styela. As, however, they agree in structure in all points I have 

 been able to determine with the account of P. pilella in the " Chal- 

 ger " Report, and are precisely like that species in appearance, I think 

 it best to place them under the above name at least, until some 

 Australian zoologist traces them in adult specimens to another species. 



Polycarpa tinctor, Quoy and Gaimard, PL Cyn. XX., fig. 9. 



There are about 30 specimens of this common Australian species in 

 the collection. It was first found during the voyage of the " Astrolabe," 

 and was figured by Quoy and Gaimard (1834) in the Report on the results 

 of that expedition. Later on it was obtained at Port Jackson by the 

 " Challenger " Expedition, and was more fully described and re-figured 

 in the Report (1882). There is nothing further to add, as the present 

 specimens agree with those of the " Challenger" collection, except that 

 in one individual examined the dorsal tubercle has the right horn coiled 

 outwards and the left inwards (see PI. Cyn. XX., fig. 9). 



Polycarpa aurata, Q- & G., var. plana, nov., PI. Cyn. XX., 



figs. 1 5. 



External appearance. Shape irregularly triangular, the anterior end 

 being long and pointed, and the posterior broader. The body is com- 

 pressed laterally, and is attached by the posterior end and part of the 

 left side. Branchial aperture at the extremity of the long narrow 

 anterior end ; atrial on a long siphon springing from the dorsal edge less 

 than half way back ; both apertures are wide. Surface with slight 

 longitudinal ridges and grooves. Colour pale yellowish brown. Length 

 8 cm., breadth 4 cm., thickness 2 cm. 



Test leathery, flexible, not thick ; full of small vessels, with numerous 

 little knobs close to the surface. 



Mantle thin, very dark in colour, slightly muscular, closely adherent 

 to test. 



Branchial sac with 4 rather wide folds on each side. About 6 internal 

 longitudinal bars on a fold and 4 to 6 in the interspace. About 6 

 stigmata in a mesh. 



Dorsal lamina a plain membrane. 



Tentacles very numerous and closely placed. 



