104 MARINE BIOLOGY OF THE SUDANESE RED SBA. 
specimen has few of the former and more of the latter. Colour of the lighter 
specimen not uniform, dark and light brown blotches and a good deal of 
dirty white pigment on the body. In this specimen the dorso-lateral processes 
are hardly branched at all, and in both only the pair just behind the gills 
have clubbed ends, which are chocolate in one specimen and light brown 
in the other. Other details as in former description, except hump on tail 
which is not so much cut off from the tail-crest.” 
The length and narrowness of the living animals, according to the above 
measurements, are remarkable. They can doubtless alter their shape and 
become less elongate. As preserved, the largest is only about 25 mm. long 
and continued into an almost globular mass. Neither the frontal veil nor the 
dorsal processes are conspicuous. The processes appear simple, but when 
expanded in water each is seen to bear 2—4 small secondary branches, which 
in their turn bear knobs. The colour of both specimens is purplish with 
yellowish ocelli. The outline of these ocelli, as well as of their centres, is 
often irregular and not even approximately circular. In other respects the 
specimens conform to the previous description. 
Mr. Crossland also notes that this species, like many other nudibranchs, 
suddenly appeared for a short time in great abundance and as suddenly 
disappeared, after depositing pink spawn, which is not of the same colour as 
the parent animal and is attached to Polyzoa. The colour of Plocamo- 
pherus ocellatus varies and appears to depend on its food, which was ascer- 
tained to be in some cases a “ dark purple-brown branching Polyzoan which 
is abundant on the underside of our boats.”” When specimens were kept for 
24 hours without food, they became very pale in tint and the colour seemed 
to pass out of the body in the excrement. 
The following further notes on the phosphorescence of the animals are 
interesting :— 
. “March 5, 1908. 
‘The specimens kept in a pie-dish, with frequent changes of water, have 
been very sluggish all day, generally half-contracted and loosely adherent to 
the dish. They are not used to the light at any time. At night found them 
actively crawling loosely extended, and even swimming by bending the body 
head to tail on either side. 
“When undisturbed they often emit a fairly bright light which glows 
steadily for about 5 seconds, goes out, and reappears after an interval of 
5-10 seconds. This is emitted from the tip of one of the pair of dorsal 
processes situated halfway between the head and the gills. (The ends of this 
pair are rarely club-shaped.) Occasional bright flashes may be given off by 
the gills. 
‘This performance may be in abeyance for some time, but all the six 
specimens regularly lit up, now one, now another, or all together. 
“On touching the surface of the water or flicking it with one’s finger, a 
