BEPOET ON THE NUDIBB AN CHIATA. 
9 
Mandibulse cymbiolatse, antrorsum sensim angustiores, processu masticatorio brcviori 
subhamato, margine masticatorio singula serie denticulorum armato. Lingua elongata, 
compressa, serie dentium unica ; dentes arcuati, cruribus angustis, acie cuspide prominulo 
et utrinque clenticulis compluribus. Penis inermis. 
The genus Fiona differs from all tbe other /Eolidiacke in having a proper branchia 
attached to the inner side of the dorsal papillae. 
A few species have been described, all pelagic in habit, which do not markedly 
differ from each other, and may eventually prove to belong to one circumsequatorial 
cosmopolitan form. 
' 1 . Fiona marina (Forsk.). 
Atlantic, Mediterranean. 
2. Fiona pinnata (Esclisck.). 
South Pacific. 
3. Fiona longicauda (Quoy et Gaim.). 
Pacific (neighbourhood of New Zealand). 
4. Fiona (?) alba, var. (van Hass.). 
Indian Ocean. 
Fiona marina (Forskal), (PI. XI. fig. 1). 
Limax marina, Forsk., Descript. Animalium, p. 99 ; Icon, animal., t. xxvi., fig. Gg. 
Fiona nobilis, Alder and Hanc., loc. cit., p. 10. 
„ atlantica, Bergb., Anat. Unters. af Fiona Atlantica, Yidensk. Meddel. f. d. nat. Foren. i 
Kjpbenh., 1857, pp. 273-337, Taf. ii.-iii. 
Ilgmenceolis elegantissima, Costa, Ann. del Mus. zool. di Napoli, III., 1866, p. 64, 80; IV., 
1867, p. 28. 
Fiona mar ina (Forsk.), var., pacifica, Bergh, On the Nudibr. Gastr. Moll., &c., loc. cit., pp. 86-88, 
pi. i. figs. 7, 8. 
„ (Eschsch.), Bergb, Beitr. zur Kenntn d. TEolidiaden. I., loc. cit., 1874, pp. 
606-610, Taf. viii. figs. 2-11, Taf. ix. fig. 13. 
Three specimens of this species were captured on the surface in the north-west Pacific, 
on June 29th, 1875, and were preserved in picric acid. 
The three specimens, no doubt somewhat contracted, were about the same size ; the 
largest measured about 13 mm. in length, 4 mm. in breadth, and 4 - 5 mm. in height, the 
length of the tail was 4 mm. 
The structure of the central nervous system was quite typical, but the otocysts could 
not be detected. 
The bulbus pharyngeus in the two specimens which I examined measured 2 '7 5 and 
3 mm. in length. The radula contained 15 to 16 series of teeth and 6 to 9 loose teeth 
(zool. chall. EXP. PART XXVI. — 1884.) Cc 2 
