57 
of Edinburgh, Session 1880-81. 
Branchial 
sac with six 
folds on 
each side. 
1 
Tentacles simply pinnate 
Opening of olfac- 
tory tubercle 
lateral ; horns 
much coiled. . 
Tentacles 
I much 
l branched. 
Opening of olfac- 
tory tubercle 
anterior; horns 
- slightly coiled. 
" Languets 
borne on 
a broad 
lamina. 
Languets 
not borne 
on a 
_ lamina. 
Branchial sac with seven folds on each side 
eight 
nine 
eleven 
3 5 
33 
3 3 
3 3 
33 
3 3 
33 
33 
3 3 
3 3 
3 3 
3 ) 
C. fissa. 
C. cerebriformis. 
C. formosa. 
C. arenosa. 
0. irregularis. 
C. ‘pallida. 
C. hispida. 
C. complanata. 
Cynthia cerebriformis , n. sp. 
External appearance. — Shape irregularly pyriform ; anterior end 
wide and bent over greatly to the right side, which is concave, while 
the left is prominent and convex ; posterior end drawn out into 
a short stalk, tapering to the point of attachment. Apertures not 
distant, both terminal, at the anterior edge of the right side, slightly 
projecting, directed to the right and a little anteriorly. Surface 
sulcated all over so as closely to resemble the convoluted sur- 
face of a brain ; four large convolutions lead up to each aperture ; 
posterior end and stalk wrinkled, but not sulcated like the rest. 
Colour dirty yellowish-white, becoming brown on the stalk. 
Length, 6 '5 cm. ; breadth, 4 *7 cm. 
Test thick, very stiff and solid ; white on section and on the 
inner surface. 
Mantle very thick ; muscular at the anterior end. Branchial 
siphon short and wide ; atrial narrower, but nearly twice as long. 
Branchial sac with six folds on each side. Internal longitudinal 
bars numerous, about nine on a fold, and the same number in the 
interspace. Meshes occasionally divided by narrow horizontal 
membranes, and containing each six stigmata. 
Dorsal lamina represented by a series of closely-placed stout 
tapering languets. 
Tentacles branched, twenty in number — ten large and ten small 
placed alternately. 
Olfactory tubercle rather large, elliptical in outline, placed with 
