CATALOGUE OF TUNICATA. 53 



The present form, however, differs from the species in not having 

 the regularity of form and marking seen in Quoy and Gaimard's figure. 

 On account of the absense of the marked sulci, I have named it variety 

 plana, and have given it the above detailed description. 



Polycarpa attollens, n. sp., PI. Cyn. XX., figs. 6 8. 



External appearance. Shape ovate, with a long anterior projection, 

 which bears the branchial aperture at its extremity. Atrial aperture on 

 a long projection, which springs from the dorsal edge half-way down, and 

 is directed forwards. Body not compressed, attached by well-marked 

 branched roots at the posterior end. Surface slightly marked with sulci, 

 otherwise smooth. Colour a dirty smoky white or yellow. Length 

 5'5 cm., breadth 2 - 5 cm., thickness 2 cm., roots extending for 4'5 cm. 

 beyond the posterior end. 



Test leathery, flexible, not thick. 



Mantle not thick, moderately muscular, closely attached to test. 



Branchial sac with well-marked folds. About 8 internal longitudinal 

 bars on a fold and 4 in the inter-space. Three narrower transverse 

 vessels occur between rather wider ones ; here and there there are 

 occasional very much wider transverse vessels. The stigmata are short 

 and wide, and are usually about 6 in a mesh. 



The dorsal lamina is a slight membrane. 



The tentacles are large and numerous, about 40, with about the same 

 number of very much smaller ones projecting from their bases. 



The dorsal tubercle is remarkable. It is large, of triangular form, 

 completely filling the peritubercular area. The slit is on a closely con- 

 voluted band. 



Locality. Port Jackson. 



This species is like Polycarpa pedata, Herdm., in superficial appear- 

 ance (PI. Cyn. XX., fig. 6) ; but is quite distinct from that species in 

 structure. The notable external points are the prolonged anterior end 

 and the large root-like processes for attachment. 



Figure 7 shows part of the branchial sac. The large tentacles are closely 

 crowded, and the smaller intermediate ones are inconspicuous, and 

 required to be found with the microscope. 



The dorsal tubercle (fig. 8) recalls that of Asciclia pyrifonnis, Herdm. 

 The double sinuous line branches occasionally, and is interrupted once 

 or twice at most. 



