250 SIR CHARLES ELIOT ON NUDIBRANCHS [ Mar. 17, 
hypertrophy of organs or parts occurred in one sex only, the parts 
affected were subjected by the habits of the animal, as known by 
observation, to special irritation and stimulation. 
Postscript, added April 25th.—On March 9th, as the left central 
rectrix in Cock B seemed to be ceasing to grow, I tried to pull it 
out, but it broke off at the top of the sheath. The total length 
from the surface of the skin was 4 feet. The right central rectrix 
in the same bird-on March 16th was 3 ft. 4 in. long and still 
growing. At present it shows no sign of cessation of growth, 
and has now been growing for more than a year. The appearance 
of the two birds at the present date is shown in the two photo- 
graphs (text-figs. 41, 42, pp. 240, 241). 
2. On some Nudibranchs from Hast Africa and Zanzibar. 
Part I. By Sir C. Huot, K.C.M.G., H.M. Commis- 
sioner for the Hast Africa Protectorate, F'.Z.S. 
[ Received February 20, 1903. | 
CERATOPHYLLIDIA AFRICANA, gen. et sp. nov. 
One specimen from near Wasin, E. Africa, in 9 fathoms. 
The living animal was described by Mr. Crossland, who dredged 
it, as of a light greenish-yellow colour on the upper surface, but 
with the foot, branchiz, and under side of mantle, white. The 
back was very hard and smooth, but its most remarkable character- 
istic was the presence of a number of papilla, consisting of round 
or pear-shaped bodies set on stalks. The stalks as well as the 
base and tip of these globes were white, but the middle part was 
black, owing toa dense aggregation of black spots, which, however, 
can be seen to be separate under a lens. The globes were quite 
soft and the stalks flexible; they shook when the animal was 
moved, but were not observed to execute any spontaneous move- 
ments. The mantle-edge was wavy. 
The alcoholic specimen is of a uniform pale lemon-yellow, the 
black bands of the globes being, however, preserved. The breadth 
across the middle of the back is 1:9 centim. Unfortunately the 
animal is contracted almost into a circle, but apparently the 
length, when stretched out, must have been about 2°2 centim. 
The consistency of the body is like hard wax, and fragments of 
the mantle, which is ample, could easily be detached with the 
forceps. The whole dorsal surface is a mass of closely packed 
spicules. It bears about a hundred of the stalked globes. They 
are of very varying size; many are quite minute, but the largest 
is about 3 millim. high including the stalk, and about 2 millim. 
across the ball, which is quite soft and can easily be pressed flat. 
They are distributed over the whole of the back irregularly, and 
not in any pattern, but are perhaps thickest round the mantle- 
edge, including the space in front of the rhinophores. Both the 
1 For Part I. see P. Z. S. 1902, vol. ii. p. 62. 
