colourless patches extend as far . as the cerebral closters reach, 
showing that the absence of pigmentation clearly depends on the 
distribution of ocelli. 
Measurements: The first given here have been made on 
the larger specimen. Total length of animal 28 mm, greatest breadth 
21 mm. Distance of tentacles 
from anterior margin of body 6 
mm, between the two tentacles 
2 mm. Male aperture I.7 mm 
from caudal margin, and female 
gonopore close to the male open- 
ing. Mouth nearly subcentral. 
The smaller specimen measures 
22 mm, with a maximum breadth 
of 20 mm, and has the mouth 
12 mm and the male aperture 2 mm from the hinder margin of 
the body; the pharynx is 9 mm long and the post-pharyngeal region 
reaches 6 V 4 mm in 
length. The interdistance 
of sexual pores isO .2 mm. 
Arrangement of 
ey es: The marginal 
ocelli are densely ar- 
ranged in rows, but only 
in the anterior part of 
the body (text-fig. 1 ). 
The marginal ocelli dim- 
inish in numbers very 
considerably already in 
the body-zone lying 
between the tentacles 
and the mouth. The 
hinder part of the body 
nearly entirely lacks 
eyes; only few observed. 
There is quite a difference between the size of the marginal ocelli 
and that of the others; the former being far less conspicuous (cf. 
text-figures). The cerebral eyes are arranged in two, but not 
Text-lig. 2. Stylochus marmoreus. Cerebral, tentac- 
iilar, and sonie of the frontal eyes of the smaller 
specimen. The interrupted lines indicate folds of 
the body. 16 x. 
Text-fig. 1. Stylochus marmoreus n. sp. 
Marginal eyes at the frontal end of the 
body. 24 x. 
