156 ARTHUR WILLEY. 
margin of body of the delicate brown ground colour inter- 
rupted by narrow white streaks; mid-dorsal region pitted 
with numerous minute black spots; tentacles brown with 
rose-yellow tip, 13 mm. from anterior margin ; large tentacular 
eyes at base of tentacles, more numerous than the smaller 
cerebral eyes; latter numbering about twenty-two to twenty-five 
on each side; female genital aperture about same distance 
from posterior end as the tentacles are from the anterior end ; 
pharyngeal bursz, seen from below, dense white; intestinal 
diverticula six or seven pairs. 
The margin of the body is always sinuous or skirt-like, and 
when at rest the animal is capable of assuming a nearly circular 
form. Both this and the following species can be handled with 
impunity, neither of them evincing the slightest disposition to 
laceration. 
Planocera discoides (mihi) is, for a Polyclade, an object 
of great beauty. I obtained two specimens of it from the 
bottom of a volcanic stone, on the top of which corals and 
sponges were growing off the south-west shore of Rakaiya, 
in some two or three feet of water at low tide. 
It reaches the length of 75 mm., with a width of 36 mm., 
always with a sinuous margin. Like the preceding species, it 
can assume an almost circular form. The body is remarkably 
transparent ; intestinal rami, seen from above, light brown, 
moniliform, anastomosing ; interspaces beset with numerous 
minute rubiginous spots; larger dark brown nodal spots 
scattered about dorsal surface ; margin of body light, pellucid ; 
tentacles pellucid, 22 mm. from anterior margin; female 
aperture same distance from posterior margin; large dense 
white shell-gland between the two genital orifices; eyes about 
twice as numerous as in P. discus; cerebrum in a clear pel- 
lucid area, which is deeply indented or excavated ventrally ; 
seven or eight pairs of intestinal diverticula, which present a 
dull greyish-white colour from below. 
P. discus laid a circular dise of egg-capsules on April 30th. 
The disc had the appearance of consisting of a series of con- 
centric circles, but closer examination showed that the rows 
