168 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
B. CotyLeA: Family—HURYLEPTIDA. 
25. Cycloporus papillosus, Lang. (Pl. XIV, figs. 41, 44.) 
Length 10—15 mm. _ Body fairly consistent, oval, 
slightly narrowed in front, where it is continued into a 
pair of short stumpy tentacles. The dorsal surface is 
typically produced into a number of small, usually brightly 
coloured papillze which are quite superficial elevations and 
do not involve the underlying alimentary canal. They are 
absent in the variety /aevigatus, and are replaced by pig- 
ment-spots. The colour is very variable and the meaning 
of this variability 1s discussed below. Peripheral clumps 
of pigment occur on the margin. Hyes are present on 
and round the bases of the tentacles, and a pair of larger 
eroups are also present over the brain, (cephalic groups). 
The mouth les behind the brain and leads into a bell- 
shaped pharynx which appears as a light area on the 
dorsal surface. The long main-gut is median and gives 
off 6—7 pairs of lateral branches. The male and female 
genital aperture lie behind the mouth in the order named. 
The sucker is subcentrally placed on the ventral surface 
of this animal. 
The conditions under which Cycloporus is found appear 
to point very forcibly to the conclusion that the colouring 
is associated and probably correlated with that of the 
substratum. Cycloporus is found often in pairs of similarly 
coloured individuals, on the surface of sponges and com- 
pound ascidians both in the littoral and deeper zones. 
The general colour is frequently but not always that of the 
particular ascidian (Leptoclinum durum, &c.) ‘The main- 
eut which is median with lateral branches, appears to 
simulate lines separating off the ccenobia, while the peri- 
pheral pigment-spots resemble in detail the coloured and 
expanded ends of the vessels of the ascidian test. This is 
notall. The sucker with which the Cycloporus is provided, 
