30 THE AUSTRALIAN MUSEUM. 



The front part of the mantle is remarkably muscular, and the siphons 

 are powerful (fig. 5). The sphincter muscle mass, at the base of the 

 branchial siphon, is 8 mm. in thickness. The invaginated test lining the 

 branchial siphon is thick and white. In its deeper part it bears a 

 number of minute tentacles (fig. 2), while nearer the aperture there are 

 a number of microscopic spines (fig. 3). I think it possible that the 

 siphons may be protruded to a considerable extent when the animal is 

 alive. 



The branchial sac is remarkably delicate, and is in very bad condition, 

 most of the epithelium being lost, so it is impossible to determine 

 exactly the number of folds. The great horizontal folds on the front of 

 the numerous transverse vessels, and the long rows of stigmata in the 

 meshes (fig. 6), give a characteristic appearance. 



The 12 much-branched tentacles form an enormous tangled mass 

 extending 1'5 cm. from the base of the branchial siphon. The larger 

 ones are very bushy, and have stout bases. 



The oesophageal opening is placed far forwards, very close to the 

 tentacles, and that makes the dorsal lamina short. 



The dorsal tubercle is 4 mm. long, 2 mm. wide, and 2 mm. high. It 

 is merely an ovate, convex, spongy-looking pad (fig. 7) 



Cynthia multiradicata, n. sp , PI. Cyn. IX., figs. 1 5. 



External appearance. Of short cylindrical form, scarcely compressed, 

 narrowed at the anterior end to a short stalk, which at once spreads out 

 into a large number of branching roots, by which a firm attachment is 

 effected. Branchial and atrial apertures both on the dorsal edge, rather 

 far apart, sessile but distinct. Surface raised into a few abrupt rounded 

 knobs, otherwise smooth. Colour a dirty yellow white. Size 5 cm. long, 

 by 2 - 5 cm. broad (dorso-ventrally), by 2-3 cm. from side to side. 



Test leathery, but rather soft and flexible, moderately thick. 



Mantle thick, opaque brown in colour, and moderately muscular, with 

 strong sphincter muscles. 



Branchial sac with 6 folds on each side. Internal longitudinal bars 

 not wide, but distinct ; about 12 on a fold and about 6 in the interspace. 

 Meshes mostly rather longer transversely, and containing about 8 

 stigmata, crossed by a narrow horizontal membrane. There are about 3 

 narrower transverse vessels between a pair of wider. 



Dorsal lamina represented by a row of very short, blunt, closely- 

 placed languets 



Tentacles about 12 larger and 12 smaller placed alternately. 



