59 
of Edinburgh, Session 1880-81 . 
not distant, prominent. Surface smooth on the posterior half of the 
body; covered with fine silky spines on the anterior half, these 
increase in size towards the anterior end and culminate in sheaves 
of long bristles, which surround and hide the apertures. Colour 
grey. Length of body, 1*5 cm. ; breadth, L3 cm. ; length of stalk, 
L6 cm. 
Test thin but tough ; semi-transparent on the posterior half of the 
body. 
Mantle thin hut muscular; muscle bands forming a close net- 
work. 
Branchial sac with six folds on each side. Internal longitudinal 
bars ribbon-like, about eight on a fold and four in the interspaces. 
Meshes transversely elongated, divided horizontally by three narrow 
membranes, and containing each nine or ten stigmata. 
Dorsal lamina consisting of a series of small closely-placed 
languets borne on the edge of a broad lamina. 
Tentacles large and much branched, about twelve in number. 
Olfactory tubercle simple, transversely elliptical, opening anterior, 
horns turned inwards. 
One specimen from Torres Straits, 3 to 1 1 fathoms. 
Cynthia arenosa, n. sp. 
External appearance .■ — Shape irregularly ovate or sub-triangular, 
elongated transversely, not compressed laterally ; posterior end 
broad and rather flat, anterior narrow; dorsal and ventral edges 
convex; unattached. Apertures both at the anterior end, incon- 
spicuous, placed close together, cross-slit. Surface entirely covered, 
with the exception of the siphons, by a close layer of sand grains. 
Colour grey. Length, 1 ‘5 cm. ; breadth, 1 cm. 
Test thin, but very stiff on account of the imbedded sand. 
Mantle thin, but strong ; muscle bands well developed. 
Branchial sac with six folds on each side. About five internal 
longitudinal bars on each fold, and the same number in the inter- 
space. Meshes square, containing each about four stigmata, divided 
horizontally. 
Dorsal lamina formed of a series of small tentacular languets. 
Tentacles compound, few, long and short alternately. 
