94. MARINE BIOLOGY OF THE SUDANESE RED SEA. 
accompanying series of figures shows the outlines copied from actual speci- 
mens of (a) a young Crosslandia ; (6) an adult Crosslandia; (¢) a Seyllaa 
pelagica from the Indian Ocean. 
It is interesting to observe that the caudal crest and the digitations of the 
wings disappear as the animals grow older. Something similar seems to 
occur in Lemanotus Eisigi as described by Trinchese. He states that the 
young animals have almost the appearance of A¥olids with separate dorsal 
papillee, but as they grow up these become united at the base, so that in the 
adult the back is bordered by a membranous expansion bearing points. 
MELIBE BUCEPHALA, Bergh. 
(Bergh: “Danish Expedition tu Siam,” Gasteropoda Opisthobranchiata, 1902, p. 205, ff.) 
Two specimens. The notes say they were found washed up on the sand 
between Suez and Port Tewfik. They were transparent and colourless, 
except for a light tinge of brown and a plentiful sprinkling of opaque white 
lots. They also bore numerous raised spots, which were white or brown on 
the body but often colourless on the cerata. 
The larger specimen is about 90 mm. long including the hood. The body 
bears no woolly or filamentous processes, but is covered with soft tubercles 
which are often compound. On the back between the cerata these tubercles 
become elongated and bear five or more short branches, but they are not 
foliaceous and can hardly be termed branchiz. The cerata have mostly 
become detached, but there were apparently five pairs and an unpaired one 
on the tail (absent in the second specimen). Their shape is very various, and 
shows that in dealing with preserved specimens this character must be used 
with caution as a specific distinction. It would seem that the cerata in their 
natural condition have a fairly long stalk which is constricted at the base, 
but in the upper part becomes gradually wider and thinner until it terminates 
in a membranous expansion which is notched in the middle (more distinetly 
in one specimen than in the other). The whole surface of the cerata is 
covered with knobs which become smaller towards the top, where they are 
replaced (especially on the inside of the cerata) by short thin papillee. 
The hood is large and its outer surface much like the rest of the body. 
The margin, which bears three or four rows of simple cirrhi 2-3 mm. long, 
is not even but deeply incised below the mouth and in the corresponding 
point on the other side. Both specimens show this peculiarity, and the line 
of the cirrhi is continued in the notches, though they are less numerous there. 
The rhinophore sheaths are small with a membranous expansion behind, 
tuberculate and with crenulate margins. The rhinophores themselves are 
yellow with only a few perfoliations. 
At the bottom of the hood is a round fleshy lip, covered with minute 
papille which are tipped with opaque white. Below it are two small 
