190 Messrs. Alder and Hancock on new British species 
Cocks among a mass of sea-weed thrown up after a storm at the 
mouth of Falmouth harbour. Three specimens were obtained, 
one of which Mr. Cocks kindly sent to us in spirits. The dis- 
section of this specimen has shown a peculiar modification of the 
digestive system which appears to have been overlooked by 
Cuvier, and the particulars of which will appear in the 4th part 
of our ^Monograph of the Nudibranchiate Mollusca.^ 
Another species of great interest and beauty is apparently 
new, and very nearly allied to our genus Proctonotus, but differs 
from it principally in a peculiar crest-like body uniting the dorsal 
tentacles. It probably belongs to the genus Janus of Veramy, 
so far as we can judge from the notice of that genus inserted in 
the Reports of Zoology lately published by the Ray Society ; but 
whether or not this may be the case, which we have not the 
means of verifying at present, the name of Janus being pre-occu- 
pied in entomology, we propose now to describe it under the 
generic name of Antiopa, and to characterize it as follows : — 
Genus Antiopa. 
Body ovate, rather depressed and tapering to a point poste- 
riorly. Tentacles four : the dorsal pair linear, laminated, non- 
retractile, and united near their base, for a short way up, by a 
fleshy crest. Head anterior and inferior, without veil, but having 
two short cylindrical oral tentacles. Jaws corneous. Branchiae 
papillose, elongated, clothing the sides of the back and extending 
round in front of the head. Anus posterinr-dorsal, on the median 
line. The digestive system supplied with two lateral trunks which 
give off branches to the papillae. Common aperture of the gene- 
rative organs on the right side. 
Antiopa splendida. 
Body of a transparent buff or lemon eolour, and rather elon- 
gated. Dorsal tentacles tapering and strongly laminated in an 
oblique direction ; united below by an arched, semicircular la- 
minated crest, which is placed longitudinally between them. 
Branchiae very numerous, large and inflated, clothing the sides 
of the back and passing round the front of the head. When held 
erect they conceal nearly the whole of the body. They are ovate, 
very transparent, of a pale buff-colour, and have a narrow, linear, 
brown central vessel, which bifurcates at the top. The apex of 
each papilla is of a brilliant opake bluish white with a metallic 
lustre, deepening into ultramarine blue below. They are set in 
about thirty transverse rows on each side uniting in front, each 
row containing about five papillin; the inner ones large and in- 
flated, those next the foot small. The back is blotched with 
metallic blue. Head subtriangular, the sides forming a kind of 
