98 
of the male apparatus. 3) Leptostylochus from New Zealand has a 
large Lang’s glandular vesicle and rudimentary tentacles. 
There are further two new species, both obtained at Amboina, 
the one belonging to the genus Cryptophallus, previously known 
only from South Africa, the other a member of the genus Stylochus, 
widely spread in the warm seas and containing numerous species. 
A survey of the general arrangement of the eyes in the family 
is included in this paper for the purpose of calling the attention of 
future investigators to this character. 
I have found it necessary to add a key of determination ac- 
cording to our present knowledge of the family. In 1913 there 
were seven genera included in the family. Since that time the 
number has been augmented to the double. 
The paper ends with a list of the geographical distribution of the 
Stylochids, revised up to date. 
Stylochus marmoreus n. sp. 
(Plate III, Figs. 1—6; Plate IV, Fig. 30.) 
Locality: Amboina. 
Mate ri al: Two specimens collected February 10, 1922, and pre- 
served in formalin. 
Habitus: The appearance of this new form is quite typical for 
the genus Stylochus (Plate III, Figs. 1 and 2). The body is rounded, 
very thick in the central parts, and thins out towards the margins. 
The consistency is, as is usual in Stylochids, very firm and compact. 
The tentacles are low and represent half-globe-shaped prominences. 
The upper surface of the animals shows a greyish brown colour 
with a violet tint. The pigmented patches anastomose freely; the 
unpigmented interspaces, being more or less inconsiderable in extent, 
give the body a marmoreal texture. The assemblage of pigment 
shows a tendency to become gathered in the central area, which 
is a common feature in brown-pigmented Polyclads. At the margin 
of the body the pigment patches are less gathered (Plate III, Fig. 3). 
The tentacles are pigment-free but for the cup-pigmentation of the 
eyes. The large number of ocelli, which to a great extent fill the 
tentacles, gives them a pronounced black appearance (Plate III, 
Fig. 4). The area above the brain, or rather where the cerebral 
eyes are gathered into clusters, is nearly pigment-free, and the 
