62 
Proceedings of the Royal Society 
Two specimens from Station 162 (Bass’ Straits), 38 to 40 fathoms. 
The larger specimen has the surface considerably more wrinkled and 
the apertures more prominent than in the other. Both are attached 
to the interior of bivalve shells. 
Cynthia complanata, n. sp. 
External appearance. — Shape elongated, oblong, pointed at the 
anterior end, flattened laterally ; dorsal edge straight or slightly con- 
cave, ventral convex ; posterior end wider than anterior, hut narrow. 
Attached by the ventral edge of the posterior end. Branchial aper- 
ture terminal, quadrangular, tubular, wide ; atrial on the dorsal 
edge one-third of the way down, slightly projecting, also quad- 
rangular and wide. Surface irregular but smooth, slightly creased. 
Colour dirty white. Length, 5*6 cm. ; breadth, 2 '7 cm. 
Test soft, cartilaginous : varies greatly in thickness ; is thin on 
the anterior half, then becomes thicker, and the posterior third is 
a solid mass of test substance. 
Mantle thin ; musculature rather feeble ; siphons very wide. Spi- 
cules in the mantle like those in Cynthia pallida, Heller, but longer 
and thinner. 
Branchial sac with eleven folds on each side. Eight internal 
longitudinal bars on a fold and four in the interspace. Meshes 
slightly elongated transversely, containing each about five stigmata, 
and generally divided horizontally. 
Dorsal lamina formed of short blunt membranous languets. 
Tentacles branched, nine large and nine small placed alternately, 
and about eighteen very minute intermediate ones. 
Olfactory tubercle. — Outline nearly circular, both horns turned in- 
wards, much coiled. 
One specimen from Port Jackson, 6 fathoms. 
Sty el a, Macleay. 
This term was proposed by Savigny to denote a tribe of the genus 
Cynthia, and was first, I believe, used as a generic name by 
Macleay * in 1823. 
* Trans. Linn. Soc., vol. xiv. 
