REPORT ON THE TUNICATA. 147 



rather narrow posterior end. The apertures are both a1 the anterior end, are moder- 

 ately far apart, and are placed on short dome-like projections, the ends of which are con- 

 spicuously four-cleft and covered with strong echinated hairs, which fringe the apertures. 

 The branchial is directed anteriorly, and the atrial dorsally. 



The surface is more or less wrinkled, and closely covered with a short down of prickly 

 hairs, which occasionally, at the posterior end and most markedly around the apertui 

 increase in size, and form large branched bristles. The colour is dull brown, rather 

 lighter around the apertures. 



Length of the body, G"6 cm. ; breadth of the body, 5 '6 cm. 



The Test is not thick, but is leathery and tough ; it is smooth and glistening on the 

 inner surface. 



The Mantle is thick, and the musculature is very strong and close, especially on the 

 siphons. 



Tlie Branchial Sac has nine folds upon each side ; the ventral folds, or those next the 

 endostyle on each side, are very slight. The alternate transverse vessels are wider than 

 the intermediate ones. The internal longitudinal bars are numerous, there are about 

 twelve on a fold, and six to eight in the interspaces. The meshes are small and contain 

 each about four stigmata. 



The Dorsal Lamina is formed of a double series of very small languets. 



The Tentacles are compound; there are about fourteen, and they are all nearly of 

 the same length. 



TJie Dorsal Tubercle is small, but very prominent ; it is situated on a hemispherical 

 projection, and is elongated transversely ; both horns are coiled inwards. 



There are two specimens of this species in the collection, both from Bass Strait. The 

 larger specimen has the surface considerably more wrinkled and the apertures more 

 prominent than is the case with the other. Both are attached by their posterior ends to 

 the interior of bivalve shells. The apertures are very conspicuous, being placed upon 

 dome-shaped projections, terminated by clumps of strong branched hairs (PI. XV. 

 fio\ 1). The surface is strongly wrinkled, and more or less clothed with short hairs. 

 The test is leathery and tough, and the mantle is thick and has its musculature well 

 developed. 



The branchial sac has eighteen folds, each of which has a Large number of internal 

 longitudinal bars (PI. XV. fig. 2, hr.f) 



The dorsal lamina is peculiar (PI. XV. fig. 3, /. and /.')• In addition to the usual series 

 of triangular languets (/.), there is a second series of similar but rather smaller and more 

 numerous processes (/.') running parallel with the first series, and separated from it 

 by a shallow groove. The dorsal tubercle is small but prominent (PI. XV. fig. 4). It 

 is simple and symmetrical, both horns being coiled inwards. 



(ZOOL. CHALL. EXP. — PART XVII. — 1882.) K -*- 1 



